Reply To: Scott Atwater 1-30

[HARRY D. NICHOLSON]

If you squeeze that coupler and then weld it, it may not fit on the splines again due to shrinkage after welding. Perhaps spline rust caused the crack due to expansion? I think your couplers are for adapting the newer, simpler, (better) lower unit. Early 509 used flat steel blades pinned to the driveshaft for crank and LU connections while later driveshafts were splined on both ends. The early 509 lower unit consisted of separate castings and therefore lots of additional seals-O-rings-grommets-gaskets. Later units were cast as one-piece in comparison.