G&R's57GMC, one thing they mention is the firm shift of the overdrive under full throttle, with the light weight of the 57 truck itself I figure I can expect alot of upshift tire chirps not only from the firm shift of a built turbo 350 but the overdrive will also provide tire chirps also, works for me.
Reading your story and your experience with the Gear vendors I see you will be investing in one for your 57 GMC, is it the overdrive you desire or do you also enjoy the "gear splitting feature" of the product?
I notice you mentioned transferring the unit from one vehicle to another, that is one thing I like, that I merely need to purchase an adapter to mount it to another vehicle. I do realize the adapter is not cheap, yet quite a savings vs buying a whole new unit.
You're the first person I have spoken to that has actually used one, thanks for your personal experience.