Well me and my dad were trying to put in a new alternator the other day and today there was a really strong smell of burning rubber and i didn't think we loosened/tightened the belt at all so i was wondering what the problem could be

 

Also my truck is a 1992 f150 custom, v6 4.9L manual trans

 

Well first off ifs its a 92 then it should be in inline 6 cyl, not v-6. Is the belts a serp or the old v-belts. If its a v-belt then its possible it is to tight. Or the burning could be oil leaking off the vavle cover and dripping on the exhaust manifold? You didn't switch the cables around on the battery did ya?(haha sorry just joking) Well thats my 2 pennies.