The E cars have tunnels intended for both auto or manual plus both sets of the bolt-holes there on the frame, not so in a 122.
The 122 auto tunnel is a bit wider than the manual tunnel.
A manual parts car is needed to provide parts (the brackets that the tranny crossmember bolt to [yeah, they need to be cut from the frame of the donor], that will then only be welded to the auto frame on three of four sides i.e. hanging out in mid air), so why not restore the four-speed donor?
Once all the welding is done and the parts are swapped (including all three pedals), there's not much room between the brake pedal and tunnel; small feet required here for the accelerator. A local chap stepped his brake and clutch pedal, that was pretty cool.
Whoops, did I get the brackets welded into just THE correct place? 'cause the motor mount are slanted way back now.
I've seen some other slick variations on conversions. One uses the original mounting brackets with some pieces of metal welded to the origianl crossmember. Sags enough that the driveline is always rubbing. U-joints get replaced on this one as often as oil.
Best,
shayne