Thank's Army. I thought you had been unhappy with the cut outs in the rear seat bulkhead.
I may just forgo the inertial reel three point seat belts and use 2 point lap belts. Might almost be easier to install a removeable harness bar between the B Pillars for shoulder straps.
The chassis plate identifies the car as P-44408-1957. According to this site, the "8" signifies a 4 speed transmission.
https://vlvworld.com/indexframe.html?VIN/VIN-60.htm
The transmission plate itself is marked:
Type – Det Nr – Tillv Nr
M3 254160 – 1450
Marked #656552 on top
Kobing Sweeden on driver's side.