C/K Man

There was talk over the last couple of years that the contract to build these trucks between GM and International would not be renewed. International moved production of all their other trucks besides the companion CV model out of the Springfield plant some time ago when they opened their San Antonio plant. That left Springfield only building the Silverado Medium Duty, International CV Series, and some Express/Savanna long wheelbase cutaways. International also put the plant up for sale some time ago. This all answered my earlier question as to why GM and International did nothing with these trucks since they were introduced, as they had basically become a market 'placeholder' with a finite life. The Silverado Medium Duty/International CV trucks were interesting combination of a GM powertrain, electrical system, and K2XX Silverado cab with an International chassis that was supposedly designed for a step-van type vehicle they never produced. They were manufactured in International's Springfield plant along with the IH MV series initially. When first introduced, there was much talk that the Silverado Medium Duty/CV would eventually get a gasoline engine option along with other upgrades and GM and IH would work on a class 6/7 joint venture truck. This was before VW bought Navistar out, after that happened no more was said. Draw your own conclusions... About the time talk started that the GM/IH joint venture was not going to be renewed, rumors started that GM would develop a new line of medium duty trucks themselves. The story is the new trucks will be part of the next generation HD's due in 2028, and will still feature a 'straight rail' chassis design that the current medium duty has. GM views this as a desirable feature that differentiates their truck from the competition. A gasoline engine option is also expected. As the current Silverado Medium Duty remains in production until September 2026 and there is still a lot of inventory available do not expect any official word for some time. I believe GM remains committed to their successful partnership with Isuzu, and all the LCF models will still be available from Chevy Commercial dealers. Isuzu is on the cusp of opening a new large plant in South Carolina and there is also speculation that this may result in new product for both Isuzu and Chevy Commercial dealers.

Notice the picture of the new 6.6L V-8? Looks like it has fuel rails on the side of the intake manufold. Either GM went back to port injection or it has dual port/direct.

Starting to hear some sketchy unverified rumors about the next gen. HD's, which some are saying should debut late next year: Revised Duramax (some say will still be a 6.6L) and a new gasoline engine, possibly an iron-block Gen VI of unknown displacement. It seems that the Gen. VI's can accommodate a longer stroke than the current Gen. V, so read into that what you will. Revised chassis also featuring the new E-coat as the light duty 2027's will have. The current HD chassis dates to 2011 with a few minor modifications over the years. A medium duty 4500/5500/6500 derivative that will replace the current Silverado Medium Duty. The next gen. HD's will possibly be built at Flint and Oshawa, and medium duty production will move to a GM plant from the International plant, which is in the process of closing. Post whatever HD rumors you hear and we'll see how accurate they turn out to be!

GM is moving away from the wax frame coating: https://gmauthority.com/blog/2026/06/2027-chevy-silverado-gmc-sierra-1500-get-new-frame-coating/

https://gmauthority.com/blog/2026/05/is-this-gmc-sierra-hd-prototype-testing-a-new-gm-gas-engine-for-heavy-duty-trucks/

Is Oshawa building LD's too? It will be interesting to see what will happen in Fort Wayne, that's where most U.S. LD's are made I believe.

Work is the Silverado Medium Duty trucks are being dropped. Dearlers are still taking orders but production ends on September 30th.. The reason seems to that International has sold the Springfield plant where these trucks are manufactured. The Isuzu based LCF models will continue. Rumor is GM may introduce new medium duty models with the 2029 Silverado HD's. The trucks will likely be produced by GM without a partner.

That is a flap that goes on either end of the cowl vent at the base of the windshield. Normally you can't see it because it is behind the fender. It is supposed to let water out of the cowl but keep hot air from the engine compartment from being drawn into the HVAC. It has a little weight on it to keep it closed.

I would like to see them bring back the E-85 option.

Monroe Equipment was the company that converted the Topkick and Kodiak.

You need a scanner that can read the ABS/stability/trailer brake systems. These are 'C' codes. If there isn't a trailer hooked up the problem could be with the plug if it isn't with your 3rd. brake light.

Sorry, should have said for 2027. I have heard rumors the Gen. 6 for the 1500's and SUV's will be in the form of a 5.7L and a 6.6L.

Any more news on the upcoming L8S? Will it be used in the 2028 HD's or is it the new 6.6L rumored for the 1500's in 2027?

'TFL' ran a piece featuring some footage of test trucks spotted in Colorado recently, and speculated that these trucks may have been powered by the 8.3L Duramax: https://tfltruck.com/2025/07/spied-are-these-the-new-2027-chevy-silverado-hd-gmc-sierra-hd-duramax-trucks-could-they-have-the-8-3l-megamax-v8/ A few days later, 'GMAuthority' posted word from a reliable source that the trucks were in fact powered by updated 6.6L Duramax diesels, and the rumored 8.3L is NOT planned for the HD pickups: https://gmauthority.com/blog/2025/07/is-the-8-3l-duramax-megamax-hiding-in-new-silverado-hd-sierra-hd-prototypes/ FWIW, I think the 8.3L Duramax does exist and is in the pipeline, but I think it's for larger commercial trucks.

I wonder if Fort Wayne will continue to build Silverado/Sierra LD's or will change to something else: https://www.wxyz.com/news/gm-moving-production-of-escalade-silverado-sierra-to-orion-assembly-plant-in-2027?fbclid=IwY2xjawLj0C1leHRuA2FlbQIxMQBicmlkETFXa3ZVc2tkakV1akxmZTdaAR4DvhDAc_l-S2xL7EtjddTFPja7i_md_WhZld8YamgVpixZNoFnKIjHf9RWEA_aem_c2TaGgBU7d_ZJJ-Sr-trEg

CAFE has to do with fuel economy, not emission controls. Emissions is EPA and CARB.

So, if the Corporate Average Fuel Economy requirements are essentially eliminated, what does in mean for the next generation Silverado/Sierra?

Sorry for not being the best picture, but this is a bore scope view of the #1 cylinder in my 145,000 mile 5.3L 2011 Yukon. This vehicle has been running on E85 about 80% of the time, never been apart.

Try a Fleetpride store.

E85 helps a lot too! I wish GM would make E85 capability at option on the L8T again.

A lot of people think that intake valve deposits are the only result of crankcase blow-by. That isn't true, a lot of the deposits are caused by the EGR affect of variable valve timing. Instead of using EGR valves like older engines did, modern VVT engines accomplish the same thing by advancing cam timing to the point that the intake valve starts to open before the piston reaches TDC on the exhaust stroke. This blows exhaust up through the intake port past the open intake valve, and the exhaust is almost immediatly drawn back into the cyinder on the intake stroke when the exhaust valve closes and the piston goes back down. The hot exhaust will condense on the cooler back side of the intake valve and port and that's what causes the deposits. Using a higher quality 'Top Tier' gasoline will reduce both intake valve and combustion chamber deposits. It's less of an issue in California due to the cleaner (and more expensive) gasoline formulation.

A friend of mine bought a new 2002 3500HD cab and chassis. This was a GMT400 series truck with the I-beam front axle and 5/10 stud wheels, and it had an 8.1L with the 4L80E transmission. Great truck, he still has it! Interesting that the last GMT400 cab trucks were actually 2008's. In Mexico, the GMT530 Kodiak stayed in production until 2008.

Yes, GMC's had a different dash and instrument cluster during that generation. Nice truck!

Sorry for the late answer. Canadian built GMC's during those years used Chevy engines.

Is that White Sands solid the same color that's on the 2026 Trailblazer? It's a nice color.