Ok you said q61, so you want a 2 axle truck?
--The rtr trucks have plastic guts, plastic housings, with '2 screw' diff covers.
-- There's an upgrade with plastic housings with '4 screw' diff covers, this has metal gears with bearings
https://m.banggood.com/2PCS-Upgraded...lixnkid=776878
You can get plastic guts in plastic housings, metal guts in plastic, or metal guts in metal.
Good luck with translations, it gets pretty creative
Pretty similar 1/16 trucks with parts compatibility: WPL, JJRC, MN, Fayee
Jerry, cool find. I didn't know there were any WPL axle sized working Diffs