That is a Viper AMU patch from the late 80's early 90's. All Maint. Units of the 57th Weapons School had names not unit numbers. I was assigned to the Falcon AMU right next door to Viper. Viper was home to the Red Flag Aggressors and they also conducted some testing. I agree that they were aligned with the 422.

i was at nellis for 7 years and i got my hat and patch from the viper AMU as the patch says. vipers was the F 16 squadron for the weapons school they all had names not squadron numbers like thunder for the A-10s, eagle and strike for the 2 F-15s i hold that helps, Neil

Nellis AFB 57th AGS Aircraft Generation Squadron or AMXS Aircraft Maintenance Squadron, but this is an older looking patch and I am gonna go with AGS. The stars are for the 422 TES Test and Evaluation Squadron