Indian swinging arms and rear wheels can also be made to fit into later Redditch frames, using an Interceptor swinging arm pin and thrust washers with a spacer on both sides, (taking care to get the chain alignment right). In the case of the later frames however, the Indian swinging arm is actually a little **narrower** at the back when you compare with the shock absorber top mountings. I trim the shock absorbers' bottom mounting bushes to the width of the shock absorber eye (both sides) to make sure there's still enough thread for the nut to fit the bottom studs securely, and fit a spacer between the swinging arm and the shock absorber on each side to ensure they line up vertically when everything is tightened up.
I would add that if you're fitting a complete Indian front end to a Redditch bike, it's easier to use the older type pre 2003(?) bottom yoke or steering stem in RE parlance (our hosts have these in stock) as the factory used a different steering stop design on later models. This is the type you want.
(Photo courtesy of ebay as our hosts' on-line parts book hasn't got a picture up yet.)
Otherwise you can end up with this.
Later bottom yokes can be modified if you have to.
Also be prepared to play mix and match with Redditch and Indian steering head bearing sets if replacing.
A.