Does anyone know the alloy of which the rear cast part of the frame on an early 70's harley davidson might be? I'm doing a custom chopper that came in today and it's getting a kawasaki zx-9 swingarm and being converted to a progressive linkage mono-shock. This is going to require that i removew the OEM swingarm mounts and either flip them to the rear and re-attach them or make some from scratch

The area where the swinger bolts up down to the rear-set area is some sort of cast steel I was just wondering if anyone knew what it might be to help me pick a proper filler rod for the job.

On a side note,

I can get some pics up if anyone i interested, it's going to be a really nice original piece it's aimed to be a raked out chopper (the front forks are as tall as i am) and it's getting the japanese bike rear end conversion along with a custom oil tank and a lot of other one-off bits here and there.

The mounting of the swing-arm is going to be the most difficult part to do. To ensure the chain lines up and the rear brake doesn't drag i'm going to have to turn a set of wheel and rear brake spacers, and possibly add or remove some material from the rear sprocket mounting surface of the rim. I need to get it mocked up a little better with some temprary swinger mounts to start measuring and aligning the true mounts.

It seems most people just move the motor and trans to the left 3/4 of an inch to get proper alignment but the customer stressed that he would really like if we could avoid moving the engine. The frame is unique to say the least the top motor mount is made from a pair of tire irons that run from the neck tube back to mid frame where they are welded again and then the both bend down and twist around each other to form the top mount. The guy has a great mind for being original but no longer has access to the machinery or any TIG experience and he really wants those beautifull TIG beads he said, so that's what i'm giving him He is also pretty torn up from a bad wreck and can't ride a hardtail anymore and is trying to come up with the most unique soft tail he can imagine...