Hello - I currently am putting a 1982 380 sec engine into my 1984 380 sl - Can I use the 1982 722.31 transmission in place of the 1984 722.312 ??

I believe the SEC transmission has an electronic speedo drive transmission vs the SL’s gear drive.

Sixto
98 E320s sedan and wagon

Were the US 107's mechanical speedos? My '83 Euro is electronic just like the W126.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

All 107s have electronic speedo from 1980.