This is John’s other CJ6 (John’s a long-wheelbase Jeep fan, these 6’s share stable space with a couple Scramblers and an M170).  Here’s what John wrote about this ‘73:

I bought this CJ6 with out any drivetrain, but it had a full cage (which I’m going
to end up modifying), and was set up for a 4.0, and 2 1/2” Skyjacker springs
originally in an SOA configuration. 

I swapped a D30/D44 combo into it, and put it back to spring under.  I then scored
some Renegade wheels for it, and put my Scrambler’s old 33x9.50 BFG MTs on it.

I have a Torque Command 999 and D300 going into it, but can’t decide on a 258
(easiest), 4.0 (makes most sense, but I would have to find one), or 318 TBI/ 360
projection (overkill by any definition, but my Scrambler already has a 380 HP 360
Chrysler in it, and I REALLY like it)

This will mostly be a DD/mild trail runner for my wife and daughter, so I should
just put the 258 in, but I know it will end up getting swapped out eventually.