I was very happy with the 2.88 in my former wagon... it barely affected acceleration and it made a substantial difference from 65 to 70mph. Around 3,000rpm's you will start hearing the throaty roar of the engine, just like clockwork. For highway cruising, the 2.88 it's hard to beat as a compromise of standstill performance and open road silence.

Ol' Yeller is an '83 turbo and presumably it sports a stock 3.07 differential. Makes perfect sense because the speed limit then was 55 and I think that I read here that the lowest specific fuel consumption occurs at 2450 rpm. Using the stock 195-70/14 tire and a little math:

Differential Gear Ratio Calculator | West Coast Differentials

55 mph => 2422 rpm.

Some have said that swapping their 3.07 for a 2.88 was "the best thing I ever did." The calcs tell me that for the stock 195-70/14 tire running at 65 mph, the revs fell by 177 rpm (2,862 vs. 2,685). If the difference that dramatic? The car does seem to be roaring a bit at 65-70 mph.

I understand that the swap is "straightforward" using an '85 turbo differential. Having never done this sort of thing before, does this mean you can unbolt the rear cover, pull one diff out, stuff the other one in there and replace the rear cover plate? Or do you disconnect the axles to the stub axles of the diff. remove the original diff, install the replacement and reconnect the axles to the new diff's stub axles? Is there oil in the CV joints or CV joint grease?

Many thanks!

I think most people are swapping out the whole diff case. The 6% difference between 3.07 --> 2.88 seems like a lot of work for little change. You'll also need to change out the speedometer to keep it accurate.

2.47:1 is good for keeping revs down, but it's a little sluggish under 2000 rpm...FWIW