1968 C20 Pickup Trans Swap Questions.... 4L80e

[StreetRodBrent]

Hey everyone,

I have a 1968 GMC C20 single cab long bed pickup truck. Purchased last year, was a California truck so almost rust free. So I have built a 357 (350 bored .40 over) with cam, heads, and flat tops and a victor junior. Making a tad over 400hp and ready for nitrous, electric fan, fuel cell, long tubes, line lock... and right now still hooked up to the stock 4 on the floor SM465 trans, and a tow truck rear with horrible gearing for anything but towing(3. or 2. something?) . Yes, not the setup you would think of in a 4800 long bed truck and go ahead and call be crazy but hey.. Its fun and thats what its all about!. But for that reason, next is a 4l80e trans swap as well as a 3.73 rear end both in the garage and ready to be mocked up, cut, grind, build, and put in. Questions are... Cross member, and tunnel modifications. Any input on where to buy, if i should fabricate the cross member out of the truck to go in, do I need to replace the tunnel, and also do I need to pull the tunnel out to remove the SM465 4 speed in it? (Was a hard time just to do the engine swap.) And then any other input on other details or parts. Planned on swapping the two peice shaft to a one piece if possible or shortening whats there and picking up the high horsepower two piece shaft carrier bearing, then hurst shifter, good tq. converter, TCI trans controller and trans cooler and all. Very skilled mechanic and ready to do it but would love to hear some input from some of y'all on how I should go about some things. Thanks!

Brent