C10 Rear suspension question

[maniago]

Oops I posted this in the E&D section by mistake.......I'll try to make this short, tho its a puzzle. Background: new to my stable is an abused '65 C10-Short Fleet. Driver side wheel base is 114.25" and passenger is 115.5'. Been hit in the front drivers corner many years ago and also rebuilt many years ago.....frame has no apparent damage back from the front a-arms (ie its straight and no popped rivets). Cab is on the frame in the original bolt down location and is straight (doors don't bind). Trailing arms are not bent, and measure the same length, are mounted in the right locations on the axle, but the whole axle assembly is shifted about 3" to the driver's side - trailing arms reflect the angle shift at the front mount (maybe 2 or 3 degrees - hard to estimate) and front end bushings on the trailing arms show long term "offset" wear.
Since everything rear end related is straight and in line the only thing I can come up with is that the panard bar (stock) is somehow too short and is forcing the axle to the side, thereby shortening/elongating the wb - BTW this is a '63 axle with the welded panard bracket vice the '65 carrier stud mount (according to the '65 Chevy manual sup). Questions: Can/should '63 axle cause this problem in '65s? Is the frame end panard mount on '63&'65s the same? If these are not issues, what is the correct center to center length of the '63 panard bar vice the '65 bar? Am I crazy?

Thanks for any help. Mick