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73-87 Chevy _ GMC Trucks => Blazers/Jimmys => Topic started by: 76jime on May 20, 2006, 08:40:00 pm

Title: RPO M40=TH400?
Post by: 76jime on May 20, 2006, 08:40:00 pm

Newbie here with a question. I have a 76 Jimmy 4x4 400 with a RPO listed M40 automatic transmission. If I understand some of what I learned here the M40 is a TH400 trans. How do you explain the fact the truck actually has a TH350 automatic trans. I'm sure the truck is all original but one of the three must be wrong, the RPO code, trans, or me (probably the latter)?

Title: Re: RPO M40=TH400?
Post by: VileZambonie on May 20, 2006, 08:26:00 pm

well someone could have easily swapped in a th 350, is there a detent switch on the gas pedal?

Title: RPO M40=TH400?
Post by: 76jime on May 21, 2006, 07:17:00 pm

Thanks for the response.  I did find the ID on the trans. today and it contains the seqence number off the vin.  So the truck has the right trans (TH350).  Still wonder why the RPO shows it have a M40 (TH400)?