Thanks a lot fellas!! I guess I kind of suspected that fixing the frame all along was the pure route, but I bought another 123 this past summer to grab some goodies off of--grote tail light, 3 point, lift assist, headlights and use on my dad's 123 (probably not the lift assist since I put a hydraulic lift on it already), but when I pulled the engine on my dad's to clean the frame, my heart sank to see the crack. I have wrestled with this question for a while, but now feel resolve to fix the frame after hearing some great advice from other collector's/enthusiasts. My dad's 123 is the whole reason why I started collecting cubs, so I hesitate to alter it in any way, aside from normal maintenance.
I am very grateful for the assurance to fix it.
Cub Cadet 123