[HWYSTR455]

IMO, 50 year old driveshafts are worthless, and I would never put anything with even OE power levels of the day in front of them. They were borderline when new.

If you're getting a new shaft made, upgrade to 1350s, period. What's the saying about the weakest link again? Yeah.

If the slip yoke is OE or old/unknown origin, it should be replaced regardless of power level.

Same on diff, if pinion yoke is OE, or of unknown origin, replace.

The new yoke MIGHT be slightly different than the one coming out, so, you MIGHT have to crush the sleeve slightly more. You can replace the pinion yoke and not have to setup the gears again if you are careful, and know what you're doing. Crushing a sleeve that's already been crushed is not easy, and it may weaken it, but you really don't know if you will have to until you try and check preload.

If the rear has a lot of miles on it, take the dive. If it goes away faster than it would have if you left it alone, it won't be by much of a margin.

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