Guys I'm just assembling a fresh SP400 Nailhead trans, and the std TH400 yoke fits onto the spline, but is too large in O/D. We have found out there is a difference, but we would like to know what the OD is of the Thinwall unit. I googled a search & found just one listing of 1.687". Before I turn down this std yoke, can anybody confirm a measurement on an (early 60's?) TH400 yoke?