The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Auto Trans swap from 4sp Hydramatic to 700R4

**jocko** · 06-16-2019, 05:56 PM

Nobody makes an o/d TH400 (if that is what you’re thinking). Libby’s recommending a 1:1 high gear TH400 (they all are) + a Gear Vendors overdrive (or something like that) behind it (separate unit). It is the best of both worlds, and bulletproof, but not inexpensive to do both. New GV unit around 3k alone. If you’ll be towing and at what sounds like lower speeds - then I would just go with the TH400 and leave it at that. Do you happen to know your rear end ratio? TH400 will require some means of kickdown linkage.

06-16-2019, 05:56 PM	#20
jocko Senior Member Join Date: Oct 2009 Location: Godley, TX Posts: 17,934	Re: Auto Trans swap from 4sp Hydramatic to 700R4 Nobody makes an o/d TH400 (if that is what you’re thinking). Libby’s recommending a 1:1 high gear TH400 (they all are) + a Gear Vendors overdrive (or something like that) behind it (separate unit). It is the best of both worlds, and bulletproof, but not inexpensive to do both. New GV unit around 3k alone. If you’ll be towing and at what sounds like lower speeds - then I would just go with the TH400 and leave it at that. Do you happen to know your rear end ratio? TH400 will require some means of kickdown linkage.