I will have to look into this area when I pull the engine and finish pressure washing the underside of the chassis.The frame crack also occurs in the area of the steering cylinder mount. Check both frame rails to. My 318 had this issue.
Check the front hydro crossmember also. The boss on the hydro unit can break off.
Theres an updated crossmember and a shouldered bolt used to update it, if the hydro case isnt broken. The update allows the hydro to shift a little, avoiding the cracked frame.
Thank you. My biggest issue welding on thin frames is I normally have the heat up to high in an effort to make darn sure I get good penetration. This sometimes causes heat effected zone issues as well. Normally I’ll chamfer or grind out the cracks and use a good copper/aluminum backer plate after grinding a bevel to get 100% penetration.N2, If you decide to weld your cracked frame, PREP IT PROPERLY! You need to drill a small (3/16") hole at the end of the crack. This prevents the crack from migrating further after welding. Bob