This thread is to help us 3rd genners or possibly an early Lt1 person in knowing if these transmissions will swap

Ok, I have a 92 bird, the 4L60 has gone bad
A local club member had a trans from a 93 Z28
Quick search showed that 93's were the ONLY year to use a trans with a TV cable and the trans code was the same

700R4 and 4L60 transmissions are essentially the same
4L60E is a completely different trans, and is easily identified by the absence of a TV cable

Now for the differences in a 3rd gen 4L60 and a 4th gen 4L60
The first thing i noticed was the TCC plug on the case
3rd gens use a white 4 pin plug and 4th gens use a grey 5 pin plug

Not knowing what each pin does i opted to swap the plug on the case
It actually plugs into a separate wiring harness inside the trans which goes to various places on a valve body
To do this you must drop the pan and swap the harness from the 3rd gen to the 4th gen trans as the 4th gen harness will not fit the 3rd gen plug
This is a pic of a 3rd gen 700R4 valve body.

The thingy near the red arrow is present in both trans
The parts missing near the green circles are new in the 4th gen trans and are what the extra pins go to

Next i swapped over the VSS and gear so my speedo would be correct for my rear gearing

The TV cable on the 4th gen is nearly a foot longer than my 3rd gen cable. This is no big deal as the slack can be pushed back towards the trans
*EDIT* The 4th gen TV cable will not work. When mounted on the throttle bracket and adjusted to maximum length it is still nearly 2 inches too short

Now for the good part, whats the same
The physical size is the same, the torque converter can interchange freely
You will not need a 4th gen crossmember for this, the original works fine
The output shaft has the same number of splines and is the same length as the 3rd gen so the original driveshaft can be reused
The original rubber mount attaches the same way in the same spot
The torque arm mount bracket is the same and uses the same rubber mount

So to sum it up, if you are looking for a direct swap, dont do it
The TV cable, trans dipstick and 2 upper bellhousing bolts are easiest removed BEFORE you jack-up the car or remove the trans
Also if you have LT headers, your passenger header may lean up against the pass A arm preventing the engine from tilting back for much needed bolt access. Removing the header before hand will save a good bit of swearing
Even empty automatic trans are HEAVY, bring a buddy and plenty of beer