The cars that had a mechanical speed have a lubrication "bore" to feed trans fluid to the speedo drive area. Transmissions that were designed for electronic speedos didn't have this lube bore & can cause problems. Not a good idea.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator