When I purchased my Viper, I found the following regarding production serial numbers:
Viper production 1977 to 1978.
Serial number range for 1977 production: 71904M -- 97999M and 60001R -- 63400R
Serial number range for 1978 production: 63401R . . .
Viper Second Production 1992 to 1993
Serial number range for 1992 production: ACxxxxx
Your serial number is beyond the listed production serial numbers but I am not certain how accurate this information is. I'd recommend further checking to be sure.