Look at this swinging arm

[2TFool]

I undid the rear axle and was surprised to see the swinging arm spring apart, as you can see in the picture. My guess is, and it is a guess, that it is a RD 400 swinging arm. My frame is definitely a RD 350 and the swinging arm fits properly at the pivot, just seems to be too wide at the aft end. It's actually 10.5 millimeters and it's the same amount at the top mounting for the shock absorbers. It had been used with the axle pulling the swinging arm together and lining it all up, but putting it all under some preload, perhaps that's not good for the welds etc.
I could make up spacers for the axle and I could also space out the shock absorber top mounts?
Would a RD 400 axle fit in the 350 rear hub but be the right length?
Looking on the Internet, they do have different part numbers. People selling them on eBay list them as fitting both.
I bet you guys have been here before, but I haven't and I really appreciate your advice,

[m in sc]

thats not a stock rd swingarm, it's from another bike

[2TFool]

I'm pretty sure it's Moto Carrera, I got some price lists and brochure downloads from 2001 2002 with the bike and although the pictures aren't great, I can recognizing some of the details. Question in my mind is is there any difference in width at the wheel between a 400 and a 350?

[m in sc]

zero difference. it pinching in when you tighten the swingarm isn't a bad thing at all.    also, that arm is made for a 350. the wider adjuster slot is on the LH side . 400s have that on the rh side.

[SoCal250]

It's normal for a Moto Carrera or other aftermarket arm to have a little extra width between the axle plates.
Your rear sets and pipes are Moto Carrera too. Pipes are Millennium GP model.

[2TFool]

Thanks guys, I won't worry about it anymore.