[unruhjonny]

So everyone (not just the OP) can see it here's what makes 1970 gauges unique:

1. housings; the housings are 1970-1972 - they are the same if they are for either rally gauge set; the clock and tach's each use a different rear cover that completes the housing; the housings changed mid 1972 when the seat belt minder was added.
2. the speedo's are 1970-1972, just like the housings, the speedo changed when the seat belt minder was added.
3. the oil/water gauge changed in either 1973, or for the 1974 model year (I cannot recall, but believe it has been spelled out here elsewhere); the early ones have the middle water temp reading as 210, while the later ones (lets call them 1973-1979) had the middle temperature reading as 220. I seem to recall reading that 1973 gauges had the 210 reading.
4. fuel gauges; the fuel gauge is a 1970-only thing, as the originals have a red/orange area in the last quarter tank (near "E") - this coloured zone was removed for 1971; the other fuel gauges are 1971-1974. Then in 1975 the large "FUEL" was replaced with a smaller font "UNLEADED FUEL ONLY" - that gauge is 1975-1979.
5. This is the last difference, and it's so small that I personally wouldn't sweat it; tach's - the original 1970 tach's are a one year only unit, which only have a single lead for a points distributor. The 1971-1976 tach looks exactly like the 1970 tach, except a second lead (reads "12v") was added for the electronic distributors. For 1971-1974 you could get an electronic distributor (Pontiac's version of an HEI) which is why the tach was changed.