I've got each of these. Front housing is the same for both. 5-speed -Sandwich plate differs - oil drain plug screws up into this from the bottom. -Tail Housing - bulkier to encase 1st gear (as well as reverse). As mentioned above the reverse switch position differs from 4 speed.
4-speed -Tail housing - oil drain plug screws into this from the back.
Shouldn't be backfiring and certainly not after a tune. As said above could indicate lean mixture. If just at idle/light throttle opening may just need to open up the idle screws a little - really should have been right when leaving the mechanic who fiddled with it. If carbs are out of balance will be idling rough. Also check timing.
I'd have thought valve of those sizes would be touching each other (on standard centres)? Not sure about using Inlet valves for Exhaust - aren't exhausts different material to withstand the heat? I cut down L series exhaust valve diametre (and of course length) to fit.
Moisabamf wrote: i hit a fuxing S10 if you didnt hear the story my dad never put the cotter pin in the thingy that holds the brake pedal to the master cylinder and when i was going to brake the thingy fell out and BAM
Looks to me like you got off very lightly if you had no brakes!