[kpbrown31]

I've searched the forum and can't find someone swapping a 4L80e into a 65 or 66. My 66 Catalina has a 400 in it now. I always assumed the 400s and 4L80es were of similar size in terms of case dimensions. I know the 4L80e is a little longer. I'm just curious if anyone has done the swap, and was raising and/or enlarging the tunnel needed? Thanks

[Sirrotica]

Almost any GM car that came with a T 400 in it, will accept a 4L80E. The closest interference point is the rear most cooling line in the 97, and later transmissions. Using a 91-96 case moves that line back to the same area as the T 400.

There are aftermarket fittings for the 97, and later cases that minimize the rear line being close to the tunnel if you end up with the later style case.

Contrary to what gets posted on the internet, there are only a few GM bodies that need anything more than occasional tap with a hammer to allow the 4L80E to fit, most tunnels require no modification whatsoever.

The early 60s full size cars that came with the Roto hydramatic, 61-64, do have a narrower tunnel that might require some stretching.

I hope that helps you out.

[kpbrown31]

Originally Posted by Sirrotica

Almost any GM car that came with a T 400 in it, will accept a 4L80E. The closest interference point is the rear most cooling line in the 97, and later transmissions. Using a 91-96 case moves that line back to the same area as the T 400.

There are aftermarket fittings for the 97, and later cases that minimize the rear line being close to the tunnel if you end up with the later style case.

Contrary to what gets posted on the internet, there are only a few GM bodies that need anything more than occasional tap with a hammer to allow the 4L80E to fit, most tunnels require no modification whatsoever.

The early 60s full size cars that came with the Roto hydramatic, 61-64, do have a narrower tunnel that might require some stretching.

I hope that helps you out.

I like the sound of this! I was actually looking for a later model case to have the split cooler lines for improving oiling, but I honestly think unless you’re running the transmission hard (which I’m not at all) then the early style is just fine. From what I’ve read a good builder can compensate for that anyways and you’ll be just fine. The older styles are easier/cheaper to come by anyways. Thanks!

[GTO JONES]

I do know 4L80E will fit the 69 A body with no problem

[Sirrotica]

Originally Posted by kpbrown31

I like the sound of this! I was actually looking for a later model case to have the split cooler lines for improving oiling, but I honestly think unless you’re running the transmission hard (which I’m not at all) then the early style is just fine. From what I’ve read a good builder can compensate for that anyways and you’ll be just fine. The older styles are easier/cheaper to come by anyways. Thanks!

I have a 93 K3500 with the early style cooling lines, it finally failed at 280,000 miles.

As Jake, from Jake's Performance, that specializes in 4L80E's has said, he sees no difference in reliability between the early transmissions, and the later design. Although GM contends, they made the change to help with lubrication. There isn't really a lubrication problem that is obvious, and there are millions of early, and late transmissions out in the field. Someone like Jake. that specializes in performance 4L80E's would have seen a problem, if there was one.

If all things were equal, I would have no problem choosing an early case to simplify routing cooling lines.

[lust4speed]

Ever since installing aftermarket parts on my '65 I've come to miss the room underneath that my '67 A-body has. I'll give Pontiac credit for giving passengers every bit of room they could in the B-body.

The '65 Catalina Safari wagon now has a 4L80e in place of the 400 and I think we had the trans up in place about 16 times. Each time it would sit a little higher and touch in another spot and we'd mark it and take the air hammer to that spot in the tunnel. Then back in place and a little higher and another interference spot. No cutting was needed but we pooched out the tunnel a little in all sorts of spots. Not enough to even tell from the passenger compartment, but the trans would have rubbed and vibrated against the body going down the road.

The bellhousing area was fine and it was tight along the main body of the newer style trans. The tunnel around back banjo fitting did need some relieving but that spot wasn't really any worse than the many other contact spots.

Definitely worth the trouble and money though. Hands on the steering wheel knocking off every shift at exactly 6,000 RPM time after time. The overdrive along with the Fabcraft 3.55's is a great combination also.

We did experience overheating at first as many others reported on different transmission forums. It was one of those things where people would ask for advice on the internet and no one would have an answer. My layman's explanation for the actual cure we found was the cooler fluid wasn't circulating because the line returns at the rear of the trans and feeds a bushing. The hotrod bushing from one of the aftermarket suppliers was effectively blocking the flow of trans fluid. My trans guy milled in a relief in the bushing and the trans doesn't overheat now no matter how much we abuse it. This is one of those times that the stock bushing would have been much better than the sexy cool piece.