I'm the guy that did the 4.3L swap into my 123 chassis. (1982 300D) It took me about two months of evenings and weekends to perform the swap, as I wanted to end up with a clean installation, and it cost just under $1K... However, I shopped for bargains and got lucky by acquiring a 1992 Astrovan engine for only $125, including the engine wiring harness and computer. The T700R4 transmission was $450, and the fuel pump was over $75. I didn't have to do any cutting of the chassis, but used a 10 ton hydraulic jack to spread the tunnel by about 2 1/2 inches to give the transmission room to reside in. It took some time to fabricate the motor mount brackets and exhaust. I have put about 8K miles on the finished product now, with no problems of any kind. It gets about 21 mpg around town, go to work driving. On the highway it will give around 28 mpg, cruising at 80mph with the air conditioning on and with 4 people in the car. It has much more performance than the diesel, is much quieter, more fun to drive, and I believe it will be more reliable and less costly to own than the diesel engine was - the 4.3L V6 was used in pickup trucks and vans, and is a very reliable engine, having been derived from the 350 ci chevrolet engine. (The 4.3L V6 is just a 350 with 2 cylinders cut off to make a V6) With the overdrive transmission and lockup torque converter, the car is able to cruise at high speeds with low engine rpms. You can view my web page on the car at: http://pages.prodigy.net/rwooldridge/mercedes.htm
Feel free to ask questions!
Richard Wooldridge, retired IBM Field Engineer
'82 300D/4.3L V6
'85 GMC S15 pickup
'94 Ford Taurus
'77 XJ6L Jag
'77 280Z 2+2
'69 Clark Cortez motorhome with Olds 455 Toronado conversion
There are more, but space prohibits....