(QUES)I am going to install a new rear main seal in a 259 in the car and having
done quite a few x brands but never a Studebaker, I thought I would ask for
the dos and don'ts from those of you who have BTDI

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First, be sure that the seal is the culprit.  Leaks are most often the
result of the rear part of the pan gasket failing.

If you pull the pan, drop the rear main bearing cap and you will
probably see that the crankshaft aft of the seal is bone dry as it
should be.

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 The oil leaks are usually the fault of the pan gaskets and front 
seal, rarely the rear main.  it's important to do the pan gasket 
effectively, which is difficult in the car.

================
Are you replacing the front seal as well?  Reason I ask is if you are, then
this will make it easier to get the aluminum filler block back in when
putting it back together.  

Also, you will need to either raise the distributor or be sure you get the
groove in the oil pump lined up with the tongue on the distributor shaft so
they "engage" when installing the pump.  It is really pretty easy to line
them up without having to lift the distributor.

I assume you have a shop manual but if not, loosen the middle three main caps
bolts two turns to let the crank down slightly to help remove the top half of
the old seal and inserting the new one.  Of course the oil pump and rear main
caps are removed.

This is a good time to clean the oil pump and remove the metal plate over the
center of the screen to clean any gunk from under it.

When you get all the parts cleaned, you will need to put the rear main cap
back on with the new seal. If the little rubber tips that extend out on the lower seal half stick out beyond the cap, trim them off so they will fit within the
cap and not be sticking out on the block when the cap is tightened.

Your seal set will have two little corks.  One is slightly larger than the
other and you can see which side they go in (under those little rubber tips).
I believe the larger goes in the right (passenger) side.  Use a little sealer
to help hold them in place and use a blunt instrument to push them into the
area they go in.

Next, use some sealer on the block to hold the pan gasket onto the block and
the back ends of the gasket go up against those little corks you just put in.
Use a little more sealer here.  (note:  a LITTLE)

The two end pieces that go at the back of the pan (and fit in the rear main
cap) and the larger one that goes between the aluminum filler block and pan
at the front, may appear to be too long.  They are NOT. The pan pushes up
against them and seals the corners. 

It also helps if you get about four 5/16" bolts about twice as long as the
regular pan bolts to get the pan held in place and draw the pan up enough to
start the short original bolts.

Hope this has helped some and if I've confused you or can help any, let me
know.

Ted Harbit Dec 01