Drive shaft diameter

[1994rcsbLS]

Getting a driveshaft made up. However a question was posed will it fit ?

Th400 to a ford 9”
Spinning 7k rpm and wanting Hp rating 950.
Am told by PST Drive shafts I’d need an aluminum 5” shaft based on the length I need/hp/rpm


Will this have enough clearance ?? Say around fuel tank( stock )

 

[Schurkey]

What is the diameter of your current driveshaft? How much clearance does it have along it's length when the rear suspension is at full droop, full compression and anywhere in-between?

What condition are your cab mounts? I have the stock driveshaft in my '97 K2500 extended-cab short-box. The right rear cab mount is totaled--body rust where it attaches to the cab. I put anyone in the passenger seat and the driveshaft rubs, and driveshaft balance weight knocks on the underside of the cab at one of the reinforcing cross-pieces.