3 Ton Derrick

[Grant Bowker]

All 3 of the upper portions attached to the head sheave are the same size, approximately 2-7/8" I.D. and 3-1/4" O.D.
The lower end of the side leg (hooked fitting) is the same size as the uppers.
The lower portion of the middle leg (closed eye fitting) is smaller, approximately 2-7/8 O.D. and 2-1/2" I.D. which is close to 2-1/2" nominal schedule 40 pipe. The size of the larger pipe doesn't match any standard pipe, as far as I know.
Another oddity is that the Body Parts List lists all three legs as being 3 parts, upper, center and lower. This would be fine for the measurements seen for the outer legs (upper and lower are large diameter, center small diameter) but I don't understand how the middle leg would be assembled (upper large diameter, lower small diameter, but what to do for the centre?)