TH400 to 4L80E Swap

[Steveman09]

So I'm preparing to do the 4L80E swap and I have a few q's

Got the truck rewired and is running on a 1994 454 4L80E PCM, new bulkhead harness for the trans is built and installed ready to go.

I need to know what needs to be done with the crossmember(s) and mount(s) for the new 4L80E trans and what drive line I need?

the truck is a 1990 GMC K3500 Extended Cab Long Bed Truck with a TH400 in it.

Could I just go buy a new driveline for a 1991-94 K3500 Extended Cab, Long Bed truck?

My plan is to find a rear driveline that will fit for the swap ahead of time, then just do the whole swap in a weekend.

 

[DGA1]

4L80E is basically a computer controlled TH400 with an overdrive. I believe that the mount will bolt right up and the driveshaft is the proper length already.

Only issue I foresee is the mechanical speedometer cable that came out of the tailshaft of the TH400, where as the 4L80E is electronic. I believe that they make retrofit housings for the 4L80E that will have the old mechanical unit.