Evan,
I'm not so sure CPP would be selling you a "new" box, like most of the aftermarket suppliers it is likely a reconditioned unit with the core charge included in the price. They don't have a shop or install this stuff so the technical level is somewhat limited.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine