Hi folks, removing manual gearbox mount from a w123 & all four 17mm bolt keep spinning. Looks like the nuts are some kind of speed nut that slides through a hole, there's no space to get anything on the nuts to hold them. Any tips on these or is it a case of cutting all the bolt heads off, cheers

Unfortunately, no. If the inserts have broken their spring clip retainers it's cutting time.

You might try lowering the transmission to put weight on the mount and lots of penetrating oil. I've got lucky a few times going that route. Not very often but it has happened.

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Thanks Mike D, tried lowering the box but no change so gave them all a good spray & will try again in a few days but looks like I'll be cutting the heads off

Try raising the transmission to put tension on them and using an impact wrench.

__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

On a W123 the transmission mount can be removed without removing the cross member. It requires a little more work and patience: remove the two lower 13mm bolts from the mount and the upper 19mm nut, then raise the transmission just enough that the stud on top of the mount can be put at an angle to the transmission allowing the mount to be slid out.

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