Good news, Lance – re; headers and 40 series Flowmasters. That’s a great combination. I wouldn’t futz with the TH400 unless you’re having problems with the TH350 – they’re decent transmissions and it’s already in the truck.

A cam kit with the cam and lifters like this one from Summit is fine: http://www.summitracing.com/parts/su...make/chevrolet - again, follow the instruction to the letter as modern oils lack zinc and it’s easy to ruin a cam if not properly seasoned on break-in.

The glove box plate is probably correct. Lots of these trucks (especially the 305 engines) were made for highway cruisers and emphasis was on improving the overall fleet MPG average. It would be easier (in my opinion) to buy a complete rear end from a wrecking yard. Their Hollander reference guide will tell you which ones will fit and you may be able to get a 3:73 posi that’s a straightforward swap. You can then list your old rear end on e-bay for a couple hundred bucks.