i want some opinions on what i should do, i have a 99 tahoe with the 5.7 with 180.xxx miles in it, had a bad knock that got worse so i parked it, in the process of pulling the motor and rebuilding it, well i found a 5.3 that my friend is not using, has wiring harness, pcm and everything, full motor, havent got the full details on the motor yet like the mileage or year it came out of. would i be better off rebuilding the 5.7 which im not sure how much will cost or putting the 5.3 in it which i can trade some stuff and basically get it for free and if so, what all would i have to change to put the 5.3 in and is it worth the trouble, thanks in advance