FRANK in the 10's : This square tube swing arm is not a club footed but a well built gusseted PRO-MADE 8 7/8" between the mounts w/bushings , with a 16mm hole , axel is 20mm, and it is 9 3/4" between the rear inside slides, dual air fittings on side rail and cross brace that is gusseted, raises shock or strut mount that you can drill your own holes or use the 5 3/8" slide front or back pre-drilled holes for the adjustment of your needs. NO DINGS,NO RUST, STRAIGHT, COMPLETE ADJUSTER W/ BOLTS AND LOCK DOWN NUTS.
COMPARE Stock arm F = 9 1/16" Between mounts, hole 13mm [ you would be twisting with real power ] axel way smaller than 20mm [ you would be twisting that too ]
I did not measure with the dust caps on so that would add a little to the square or the stock F arm. But we race on a mostly clean tracks, so no dust caps but special made bronze bushings [ with anti size both sides ] so you can move the tire to the right to stop tire slap or sidewall wear for a [ bigger -wider that stock rear tire ] you must have welded a ground down front sprocket onto another front sprocket to get that tire spacing in the old dayz !!!!!! then the dam chain wore a hole in the frame down tube = loved those KZ make one thing better makes a problem at another point.