TH 400 Transmissions

Bronze Dancer · 02-17-2003, 12:27 AM

As my '85 has a few issues and I'm a project nut, I just bought a used engine and transmission that match those in my '85 325. Both blocks have the same numbers and both TH 400's are '84 code FI units with serial #'s 6000 apart.

The plan is to rebuild the units, pull the existing units and replace with rebuilts. Parts question: What TH 400 do I have? (Later I'll have a bunch of engine questions for 74Argosy24MH John--I've seen his pictures).

A while back there was a mention of the TH 425 Tranmission on the forum and, as I recall, Fred's website lists the '85's as having 425's. GearVendors catalog lists no 425's but does list 475's

I just got a book loaded with codes, model numbers and interchange data. I see only one mention of the AS 425. It says "Front-drive Turbo Hydra-matic 425 interchange note......" (GMC Motor homes, Toronados and Eldorados?).

The code listing identifies 1973-82 Chevy, 14,000 GVW "Mobile" (I think they mean "Motor") Home chassis as having TH 475's. '83 thru '88 "Mobile" Homes and school buses are shown as 475's
My '84 units are both have "FI" codes and are shown as 475's

Some P chassis and other "Mobile" Homes are shown with straight TH 400's.

The only description in the book of 475's identifies them as having internal parts for heavy duty use the most obvious of which is straight cut planetary pinions.

OK all you gearheads out there, tell me your year and code and let's see what the book says so we can get Fred's website up to snuff.

Jim with the TH 475.

74Argosy24MH · 02-17-2003, 07:05 AM

I'll take the rap on this one. Back when Fred started the matrix I said I had a 425. I talked to my tranny buddy and he told me, as usual, stay away from transmissions. The 425 is the front wheel drive, 475 is the hd version of the 400. Please don't kill me Fred, I am too young and dumb to die.

John