Unicorn 2500 Chevy

Torso Jenkins · December 18, 2021

Sorry if this is posted in the wrong forum, this truck really doesn't belong in any category they have available.

I have a 2WD, 1999 Silverado 2500. It has the 14 bolt 10.5 inch, according to RPO code is a 3.73. But as factory option has a 5.3 and 4l60. I 100% know it came from the dealer this way because my step-dad bought it new in 99. He recently passed, I bought the truck from mom. So I know it's provenance; there was never a swap done or anything.

I always assumed tranny was a 4l80 until I became owner and made it a point to get to know the truck better. It made a lot of hauls to the auction barn 15 or 16 head of Black Angus every trip. Still shifts okay seems to be holding up at 286k original miles but was maintained within am inch of its life.

Just wondering if anyone has heard of this option or.knows why they built it this way. It's the only one I've seen in the wild. I know that 99 was a wonky year with big changes in drivelines and different gens of engines available same year.

Any info or anecdotes anyone has heard would he interesting. Thanks, yall.

CamGTP · December 18, 2021

I've heard of trucks made like that but it was always hard to find proof. I remember years ago that I saw a very early 2500 with a 5.3/4L80e combo truck too. I wish I would have grabbed the VIN number for it.

I think because of how unique you say your truck is, maybe post pictures of the truck and VIN/RPO tag. Would be neat to see that stuff.

Torso Jenkins · December 18, 2021

CamGTP I will do that as soon as I'm able. Will be this evening sometime.

doverarjim · December 18, 2021

Is it the new body style for 99? I had a 99 with the 6L motor and I do remember looking for parts one time and seeing that they had the 5.3 or 6.0 but I could not figure out why, unless it was to help corprate fuel numbers. :jester:

Torso Jenkins · December 18, 2021

doverarjim it's NBS. Fuel economy was what I think also. One thing I forgot to mention is that it's listed on the registration as a "2500 e". I assume e for economy.