rdrafting

I have a 91 cherokee with 160,000 miles stock everything as far as I know. It has worn a groove in the steering knuckles where the guides for the caliper ride I think? (front breaks don't work) So I need to replace both knuckles. However I bought a used dana 30 axle same gear ratio but the year is unknown. This used axle has a two piece knuckle on it, meaning that the piece that has the groove worn in it will unbolt and can be replaced. Has anyone else ran into this and can you swap these knuckles strait across?
PS. Sorry about the length.