I am about to tackle replacing the rusted out tailpan and drop my gas tank to replace the sending unit on my 91 K5. The gauge says 3/8 full when the tank is empty, so am I thinking correctly the first place to start is the sending unit? Any reason while I am there that I should replace the gas tank and the fuel pump? Just figure now's the time to do it while it is all apart. Where's the best place to get a qualitt fuel pump? Also, did 91 K5s only come with the 31 gallon option? I can't find it saying it had a 25 gallon tank anywhere. Appreciate the help!