A rebuild kit will work fine as long as you can get the old one apart (pistons out) and if the pistons aren't pitted with rust. If they are stuck too hard they are probably messed up anyway and you should just replace the whole thing.

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1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k