You could use a 5spd out of a Sprinter (been done here) also you could use a Fiat box of the same era , also been done , both require a bit of engineering , but you expected that, eh.

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'72 240D
'76 300D
'88 300sel
'40 Chev pickup , the shop hack.
'73 Monte Carlo Landau, for "Super Chevy Sunday"