I swapped a spicer from. A 72 dump truck into my bus, you gotta bump second to get the synchros going to get 1st from a stop. But I'm sure modern spiders have 1st and reverse synchronized. Spicers are beefy. Some people say they don't shift as smooth as an eaton m. I don't know I never drove one. Bottom line, in a rv application, your unlikely to
Ever break a spicer 5speed as long as you keep the fluid full.