[SS Tim]

There were no short wheelbase C20s 67-72.
The standard C20 frame is a 127" wheelbase (54"CA).
The standard C30 frame is a 133" wheelbase (60"CA).
Many C20s have coil rear springs.
All C30s have leaf springs.
Both the C20 and C30 Longhorns were built on a C30 frame and sprung accordingly with leaf springs.



C20 127 6.11" height 2.46" flange width 0.194" thick 3.71 section modulus

C20/30 133 (Longhorns) 7.20" height 2.77" flange width 0.194" thick 5.05 section modulus

C30 157 8.18" height 2.97" flange width 0.224" thick 7.29 section modulus