Mountains Garage: The Mysterious TH375 Transmission.

[@nickthevanman9011]

This video was an absolute lifesaver! I'm putting together a little budget bracket racer for the No Name Nationals, a 1987 Astro van. And I built a free 305 with basic parts and have $1400 all in with machine work, had it dyno'd at the local automotive college. And got a free....what I thought was a th400 to put behind it. Started measuring for a driveshaft and was dumbfounded how the old grenaded 700r4 measured 30 1/2 inches in length and this "th400" measured 34 1/4 inches. The long tailshaft was weird...but I said hey, it's a 400 turbo who cares I'll have the driveshaft shortened. My transmission man comes today to pick it up, and tells me it's a th375. I panic inside a bit, but he reassures me my rebuild kit for a th400 will work and that it'll be a fine transmission and plenty strong for my homegrown 305 and somewhat light vehicle. I come home, and watch this while eating dinner and learn all about it. Cool thing is it'll work with a new th350 yoke I already have ..saving money already. Mines date coded 88, in case you are curious. 88 model year, that same LSA designation, and it's a non lockup , looks genuinely like a regular old th400 just has that squared off tailshaft.

[@goldcat1844]

My Dad was a tranny builder in the 80s. I remember hearing him curse the 700r4 and AOD seriously.

[@Tripleblack94]

I bought a 90 ss 454 truck transmission.! And it does has the 27spline output shaft

[@monkeywrenchization]

Can't answer your question about the SS 454 trucks, but GM made a couple of different 375s. One was the 400, with the 1310 yoke (350 sized yoke) and less plates, the other was 375B, a 350 trans with 5-5-5 plates in the clutches. I have a trans just like you have , that I got from an old wrecking yard that was going out of business. It came from an 86 van as written on the bell, but did not give engine size, or if Chev or GMC. It had the long extension housing with the 1310 yoke. It also has HD cast in to the right side of bell, and six bolt holes for the converter shield. It had six plates in fwd, five in direct, three in intermediate. Had a shallow pan. Somebody must have been in there before. I changed a lot of things, one was, ditch the long output shaft, to put in my 62 C10 truck.

[@m2pmd70]

My 375 is still matched with the Pontiac 400 it was born with in a '73 Catalina. Supposedly the local Pontiac guru added more clutches and "made it better than a stock 400" when he rebuilt it in the '90s, before I put it in my '70 Lemans. I currently have it out for seals and gaskets. Apparently a dirt dauber clogged the vent tube. 🙄

[@patveltri8531]

Thanks for the video! Excellent as always!

[@MHolt3573]

I love the history lessons sir.

[@amateurism1]

Love this video thanks

[@stevenbelue5496]

I have a couple of these laying around, one is out of a buddy's truck he said was an 89, v8 long bed. One has a casting line that looks like it would be scribed perfect for cutting the bell off, the other has a casting line further back around the cooler lines. Yrs ago I pulled one from a 3rd gen truck with what i remember from the tag (somewhere up front, core support maybe) was a v6, 262 I think.

[@brettwelsh2550]

We use the 375 for demo derby after we exhaust our built 400's just change the shaft and clutches like you said

[@davidreed6070]

I always wondered about them, now I know. Thank you for that.

[@lightingmike1242]

I have a 375 behind my 500hp 355 and a 3000 stall for the street. Its doing good so far,

[@Huggins137]

My neighbor has a SS 454 truck I will ask him what it has for an output shaft. You should do a TH350 video build

[@BBBILLY86]

I have a 1972 Olds Vista Cruiser with TH375 9 inch tail.

[@glennrussell634]

Hi from Australia, just got a second hand (thanks to your video I can now id as a 1986 TH375) it's exactly the same as yours 86 LSA HD case with flat top on the output shaft. Did your end up having the same amount of clutches as a th400 or the same as the 70's th375?

[@sydneymartin8282]

Mine split about 6 inches above the tail shaft from pan to pan so can I take a regular turbo 400 and bolt the long flat tail on it and run it because I have had a hard time finding one

[@vrg69]

Just curious I've got 3 th400 all short tail houses I was having problems finding a yoke that would fit them all the yokes would slide in about a inch and hit the bushing in the tail housing are they actually 375 transmission

[@grumpymadvanner]

Those th400's used a bolt on yoke. There are slip yoke conversions available for them.

[@levilandes2979]

I brought home 3 cores over the weekend and noticed that 2 of them have about a 2 inch wide band where the aluminum is thicker going straight across the body of the trans..not sure of what that is

[@mountainsgarage]

Interesting!

[@gregorylytle7537]

I have a 1978 Chevy long bed truck with a th375 I want to know what is making it chew up governor gears I have done put 3 new ones in and it keeps stripping them

[@mountainsgarage]

I have seen this with worn bushings either in the tail housing or the case.

[@StevenCrowtown]

I have a TH375 in my 1972 Pontiac Catalina. It slips in gear so I'm looking at a rebuild if a stop slip juice doesn't help. Can I use a TH400 kit, and just leave out a clutch on each of the bigger bands? Rebuild kits specific to 375s are hard to find.

[@j.finesseflights1403]

Didn't GM have a big block 6cyl 305 engine?

[@mountainsgarage]

The V6 based off the 348/409 engine I believe.

[@grumpymadvanner]

GMC built v6 and twin 6.

[@BBBILLY86]

The TH375 in my 72 olds needs a rebuild. Ive kicked around buying a TCI BOP Th400 9" to replace the TH375. But they come minus tail housing and say to re-use yours. can you use a 9" Th375 tail housing on a 9" TH400?

[@skutahuniai4830]

More volume please. I'm wide open.

[@sydneymartin8282]

I have a 88 that has the th375

[@gerardolopez5875]

Just bought a 89 gmc, found out it has the th375, Will this transmission hold the 6.0 power,? Planning on swap a6.0 on it, and use the 375

[@jimchevy4134]

Hmm that's what transmission I have inmy 86 c10