can i use sierra uprights with that adapter from gts on book wishbones or is there other adjustments i need to make.

you cant use book wishbones.

The bottom joint is different, (unless you get your sierra hubs bored by MK engineering).

Also, I doubt the pickup points and vertical difference between the upper and lower joints are the same.......

atb

steve

I would go with cortina uprights if you can can find them. They are lighter and need no adaption or different wishbones to fit. If you are using a sierra donor then obviously use the ones on that.

Adam

I have a spare pair of cortina uprights.
Make me an offer if your interested.