Plenty of E36, E46, and E39 guys have swapped from auto to manual trannies. I don't know of any X5 owners that have done it. I'm sure finding a manual X5 trans is not easy either.

I have seen rebuilt transmissions range from $2k to $4k + install.

200k isn't as bad as it seems, if the rest of the truck is in good shape, I would do the trans and cross your fingers for another 200k miles. The truck won't be worth much with a bad trans, but you could try to sell it that way.

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2002 X5 4.6is - Titanium Silver / Black Alcantara - Dinan Stage 2 - Bilstein/Eibach - Brembo BBK ----SOLD---
1993 318i - Brilliantrot / Tan - bone stock daily driver