I have a 1982 240 D automatic transmission. I have a 1982 300 D parts car. Can I use the 300 D rear axle in the 240? Should I save the 300 D parts car? Can I use the engine and or trans latter on down the road? My 240 is close to mint condition, except that the rear axle will need to be redone at some point down the line due to the bad boots. Thanks for all your help.

Yes, the axle will interchange between these cars. The only thing is they are most likely different ratios. A little research should come up with ratios of each, or simply put the car in neutral with the rear wheels off the ground and count the number of driveshaft turns it takes to turn the rear wheels one revolution. That is your ratio.

Hope this helps,

The 240 rear is 3.69, the 300 rear is 3.42 (I think). You will sacrifice what little acceleration the stock 240 auto has for slightly better fuel mileage and lower cruising RPMs. You will also have to swap out the speedometer as they are calibrated to the rear end.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

I would not expect better fuel mileage by going to a higher (lower numerically) rear axle ratio on a 240D. The loss of torque multiplication is just too great. This will ultimately, however, be determined by your driving style and route.

Good luck,

The axles will interchange OK and there's nothing about gear ratios involved.

The other two guys read the question wrong.

If you save your 300D parts car many things will interchange. The engine and transmission will fit from one to the other, although it will likely involve transferring some support brackets and the drive shaft as well.

Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

yeah, if it is just half shafts we are talking of no diff.

the ratios are 369 for the 240 and 307 for the 300d unless it is a euro then it is 346 (non turbo ratio).

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Yep, Ken is right, I read the post quickly and thought that you were referring to the center section.

Sorry 'bout that,