calibrate gauge

I recently just bought an aftermarket gauge cover, to give it some spice, and to install it on the 96 tahoe, you have to pop the needles off, so silly me i just laid it flat and popped them off not really noting the position, cause i thought it will re calibrate itself. Does anyone know a way to recalibrate the needles or do i have to take it to a shop and have it professionally done? the tach and speedometer arent to far off as i turn the car on ACC and fixed them but wanna fix fuel, battery, oil, and temp. Thanks in advance guys

i have after market guages also i would recomend looking at a another tahoe and see where his guages are and try to place them there other than that bring it to the dealer ship

what i did was, turned the engine to acc and u can calibrate your oil pressure that way, another thing i used is the governor for the speedometer (which is 100), and the tach i set by just knowing my car, cause i know at 70 its at about 2k rpm's
the gas i knew cause i filled it up afterwards, the battery, i did just it up so when the cars running its in the middle (cause i knew battery was fine) and for the temp, i set it at 100 when it was idle or on acc, cant member