Quite a few years ago a friend asked me to replace the old rope main seal on his 1950 1ton dually dump box. Mind you it came off an old farm. I agreed to do the job, slid the tranny back, dropped the main caps off and much to my surprise found that the block was babbit while the caps were inserts?!?! Craziest thing I saw, but it works, the truck is still going strong and its been 20 years since I did the rear mainseal and clutch.