I am part way through a 308/4spd project and still have some unknowns. I am
using the 61 Hawk 4-speed bellhousing with a Muncie M21 and one of Ted
Harbit's aluminum flywheels. Using a B&B pressure plate and 10.5 disc.
What's missing is the proper throw out bearing and carrier, and of course
the pilot bushing. I have had recommended to me to make a carrier that
will fit the center hole of the flywheel to take a sealed ball bearing. I
have also been told to have a sleeve made for the T/O bearing carrier
(stock Stude) to bring it to the proper size to slide on the Muncie
bearing retainer snout. Any thoughts on how to finish this?

Sep 2004
////Use a Chevy throw out bearing, and machine a pilot bearing adapter. (One 
that has a step down to fit in the Studebaker crankshaft, than extends 
  out to except a bushing for the Chevy main shaft.)///
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Is the pilot shaft on the M21 (a Chevy T-10 for that matter) the same as the
Studebaker T-10 used with the Chevy bolt pattern bell housing (with the
exception of the pilot bushing diameter)?
-Dick-
   /////Except it's shorter too.<g>////
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 How do you make the shorter Chevy shaft work?
   /////You make a adapter that plugs in the Studebaker pilot hole, extends
   out, and has the correct bushing for the Chevy mainshaft in the
center./////
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I've been involved in a project to put a Camaro T-5 in place of a T-10 with
the Chevy bolt pattern in my Hawk.  This is what I've done so far.
1. Machined a new pilot bushing out of Oillite, longer than the Stude and of
the correct diameter for the Chevy T-5.  As JP says, with a collar like
flange against the crank.  This locates the input shaft of
    the T-5.
2. Cut off the "retainer" part of a bearing retainer from a T-86 parts
tranny, ending up with the sleeve part.  Slight machining of the I.D. allows
a shrink fit over the T-5 bearing retainer.  This allows use
    of the Stude T.O bearing.
3. Stude pressure plate is used with the Chevy clutch disk.

My only remaining issue is finding/cutting/making a driveshaft.

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 early Stude 4 speed has a wide bolt pattern on the top (Chevy style)