It's almost always best to start fresh, but I do understand being on a budget. I would not go cheap on the gears though. That could leave you stranded.
How many miles are on you truck? If it's not too many you could get away without changing bearings.
Marlin sells Yukon gears. They sell Yukon gears because they've had the best luck with them. Check their web site for prices.
That luck did not last to me, got bad 7,5" front RG from Marlin.
