gage cluster replacement

[66redw/white]

ive been having some problems with the gage cluster on my sierra. first off the oil pressure gage does not work any more. thats a pretty important gage to not have working. but the speedometer is real finiky as well now. sometimes it gets stuck at 55. sometimes it just decides to read 15 mph faster than im really goin. it seems to act up more in the rain if a tire spins. i think the teeth on the needles(if thats what they use). has any body ever fixed a problem like this? sounds like the old aluminum foil in the bycicle handle bars trick might work. ive been thinkin of just replacing the cluster as well. maybe using one that has a trans temp gage. any advice or experience would be greatly appreciated!