Turbo 350 or 400

[babyburb]

I am trying to figure out what tranny I have in my 76 3/4 ton burb. It has a sb 400 motor and 203 tc. The glove box list only has it listed as "HD automatic turbo". I have had 2 people look at it and 1 says turbo 400 1 says 350. What is it? Where on it can I find a part number to cross reference it?

Another ??. The list in the glove box says it has a Locking Differential. What kind of locking mechanisms where put in back in the day? Should I stick with this or save for the Detroit?
Thanks for the help.

 

[scooter122983]

I can only say about the trans is look at the pan shape and cross reference it with a haynes manual or even a lmc truck cat. Locking dif is the dreaded Gov-loc, save up and buy a selectable locker.

 

[JpEater]

My money is on a TH350. If it is a 350 is will have a square pan with a corner cut off and won't be very deep.

 

[big dan]

and a 400 looks kinda like texas. and it also has a 14bff so the gov-lock will be stronger and less prone to exploding like it does in the 10b. also if you want a detroit you'll have to get a open carrier since it wont fit in the gov-lock carrier.

 

[MTMike]

Easiest way to ID is by the pan:

TH350:

TH400:

And I'd place bets on your locker being a Gov Lock

 

[diesel4me]

look for..

The vacuum modulator is located on the front passenger side of a TH400,next to the bellhousing--a TH350 has it on the back next to the output shaft on the passenger side..its a small canister about the size of a shot glass,with a vacuum hose plugged into it..

The TH400 pan looks like a map of illinois,while the TH350 has a squared off pan with one corner at a 45 degree angle,and has 13 bolts..not many K5's had a TH400 factory,if any,so I bet yours is a TH350 unless someone swapped in a TH400 and its adapter..

 

[goldwing2000]

..not many K5's had a TH400 factory,if any,so I bet yours is a TH350 unless someone swapped in a TH400 and its adapter..

He has a Suburban.

I am trying to figure out what tranny I have in my 76 3/4 ton burb.

 

[76zimmer]

I vote 400, cuz my 78 had one in it....so it has to be.

 

[diesel4me]

ok...

OK,if its a 3/4 ton Burb,then it MIGHT have a TH400--but very few came stock with them..mostly only "camper special" 3/4 ton and up pickups were equipped with TH400's,and you had to special order it that way..

For every 100 TH350 4x4 trannies I've seen,there was about 10 TH400's..they got a bit more common in the 80's,but they used a lot more 700R4's than TH400's then too..I had to identify hundreds of tranny's at the parts stores--few people know which one they had for certain,and usually bought the wrong filter and gasket kits....

 

[76zimmer]

m-38 I believe is 350 m-40 is 400

 

[babyburb]

It does have the CAMPER SPECIAL emblem on the tailgate and says it is rated at 10000 lb towing capacities. ???????? I haven't had a chance to get under it to compare the pan on the bottom though. Maybe this weekend.