Driveshaft: A V8 will require a shorter driveshaft than all the other factory engine combos. There are basically 3 factory driveshaft lengths available. The longest is the 4-cylinder 4-speed or C4 driveshaft with a 7.5" rearend. The next shorter by about 1.5" is the V8 and 7.5" rearend. The shortest is the V8 and the 8.8" rearend combo that is still another 1" shorter. If you are going from the longest to the shortest in the 3 combos above then plan on getting your driveshaft cut and rebalanced (about $90) or get the right shaft. The length you are looking for is 45.5" from center to center of the holes for the U-joints. This length will work for any 1979-1995 Mustang / Capri 5.0L with T5 / SROD / C4 / AOD transmission and either a 7.5" or 8.8" rearend. The slip yoke on the T5 / SROD / C4 / AOD transmissions are all the same at 28 spline. The flange for the rearend is the same for the 8.8 and 7.5 also, but a 9" is different. Another couple of options are the FRPP aluminum driveshaft or the '93 Cobra driveshaft. Both are able to handle higher torque due to larger diameter shafts and bigger U-joints.
You seem to have a good amount of knowledge about the driveshafts. Would you happen to know what the length from center to center of the holes for the U-joints for a 4-cylinder 4-speed or C4 driveshaft with a 7.5" rearend would be?
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