Transmission size?

silverado3500 · February 4, 2003

Ok, Here we go, im looking to put a 2wd 1500 ex cab short box powertrain (engine/transmission) on a 4x4 2500hd ex cab short box frame. My question(s) are

1.are the 4l60e and 4l80e trannys the same length

and

2. will my 5.3 be able to be mounted to the 2500hd frame or (i want to wait on a new engine until the new ht3 496 comes out end of this year at which point ill be upgrading to either a 4l80e or allison as well)

Any insight would be greatly appreciated!

SoMnDMAX · February 4, 2003

1) No. The 4L80-e is about 4" longer than the 4L60-E.

2) I would assume the 5.3L uses the same mounting setup as the 6.0L, since they are of the same family. The 6.0 is the standard engine in the 2500HD.

Colorado Kid · February 4, 2003

Let me add to that the the 2WD and 4WD versions of both transmissions have different tailshafts and tailshaft housings, your 2WD 4l60-E will not mate up with the T-case on the K2500.

It's possible that you could mate the 5.3 with a 4L80-E, but the "right" torque converter won't exist...the 5.3 is going to feel doggy with the relatively low stall converter and taller low gear in a 4L80-E. Also the PCM is going to be a problem...there isn't one from GM that talks to that engine/trans combo.

This certainly seems like a difficult way to get a not very good truck. ???

silverado3500 · February 5, 2003

When I do the tranny swap, ill be going to the 8.1 engine (ill borrow the pcm from a suburban 2500) the 5.3/4l60e will only be temporary until the new 8.1 (hp3 i think) comes out.

Im just trying to figure out if the 5.3/4l60e will mount to the 2500hd frame for the time being, without hooking up the transfer case.