I've had my 51 Willys truck since 1980.  Recently I decided to do a repower since I had a VW TDI motor available.  And the people at TDIJeep.com in Vancouver had done it and were willing to help.  I'm making good progress on the switch.  There are pictures at:  
https://1drv.ms/f/s!AtV03aEpd79qh_ZQ1C9SCTmCmYhrewI've run into a bit of a snag.  The front differential on the Willys is offset to the passenger side.  I have a 3550 transmission, bell housing, clutch and transfer case from an 05 Jeep.  I have them all connected to the motor (got an adaptor from the people in Vancouver).  When I connected the transfer case, I looked at where it is going to go and realized the output on the new transfer case is on the wrong side!!
A DANA 300 from the 1985ish CJ's has the output on the passenger side.  NOVAK makes an adaptor.
Two things:  first, does anyone need a transfer case - you can see pictures of it above.  It's in great shape.  I have all the linkages as well.
Second, does anyone have a DANA 300 transfer case they would like to sell to a good home??
  Bob Hamilton in NW Calgary