5lm60 to THt400 swap questions

[highperf4x4]

Sweet. I'll actually have reverse lights! They've never worked since I bought the truck 12 years ago.

As for the splines, they are correct apparently. That last pic of the t/case is bolted to the TH400 that I just bought off of craigslist for 200 bucks. It had an adapter plate on it already that bolted right up to my transfer case. I'd call that a score. Now I just have to drop it off at the shop for a performance upgrade!!

 

[TylerZ281500]

reverse lights being out could be the curcuit boards or trailer harness or a slew of other things on these trucks. not too uncommon that they dont work to be honest.

id definitely call that a score just making sure everything connects for you properly, the 5 speed truck we converted to a built 700r4 we didnt do our homework on that part, bolted the stick trucks tcase up to the 700 and fired her up but she didnt move, the input for the tcase was about an inch smaller in diameter than the output the the 700r4 and wasnt even touching to engage.

 

[TylerZ281500]

also while your at it doing the seals and bushings that most comonly wear now would be a good idea.

 

[98_k1500]

That th400 output shaft is the same as the 4l80 and the same as any 5 speed offered in these trucks (assuming all are 4x4 that is). Looks like you are in the clear. The TH350 and 700r4/4l60s use a smaller output shaft, and require the correct input shaft in the transfer case.

 

[TylerZ281500]

^ thatd expain it

 

[highperf4x4]

also while your at it doing the seals and bushings that most comonly wear now would be a good idea.

Which seals and bushings?

I dropped the tranny off at the shop today and I left the t/case with them as well to replace the seal on the front of the t/case (around the input shaft) and the seal at the back of the t/case for the rear driveshaft. Oddly enough the t/case lost very little fluid over the years and the only place I could see any evidence at all was on the bolt flange for the front driveshaft. Like when I unbolted the front driveshaft it seemed like there was fluid inside the flange. All I can see in there is big nut and washer. Can it leak from inside that flange?

I'm not sure what bushings you're referring to but if they're in the t/case they probably need replacing. Any info would be appreciated. The case has over 400,000 miles on it. lol

 

[highperf4x4]

Another question. I read somewhere that there might be a heavy duty dust cover for these th400s. A thick aluminum one that helps strengthen the bellhousing. Anybody know if that's correct? If it's true I could use one. The alignment pin holes are roughed up and the bellhousing is cracked at one of the bolt holes. Apparently they abused it quite a bit with the bolts loose at some point. I'm going to have to have it welded at the crack and install longer alignment pins in my block. Any strength I can add will be needed. My 383 is only pushing about 425hp but the tranny is being built to withstand up to 1000hp so I can run a big block later on.

 

[TylerZ281500]

theres a bushing and seal in both the trans and tcase. the bushing you dont have to worry about much on the trans because its 4wd, but sometimes people have issues with their tcase ones wearing out and causing issues, since you said it all seems to look good id assume it is but never assume lol. a 400 is fine for even a big block in most cases in stock form.

 

[highperf4x4]

Yeah the tranny is being completely rebuilt and the second gear drum is being upgraded which is the weak point in a 400 it will come back from the shop capable of 1000+ hp. The problem is the crack in the case and the damaged alignment holes. Do you know if there is a heavy duty dust cover for the 400?

 

[TylerZ281500]

you can buy seperate bellhousings for em, at least when i looked into how to swap in a BOP 400 trans to a 6.0L i saw there were heavy duty housings that you have to cut the factory one off and bolt it to it i believe.