Caution: Dana-Spicer has not made 3:31 for some time. Years ago. When made, the large-pinion were HD Vette gears, and WOULD work in a Viper IF you can find them. But they are likely NOS or used. BE CAREFUL! The small-pinioned 3:31 gearset would have to be pinion-sleeved, and NOT recommended for 500 lb-ft torque!! Get the non-sleeved 3:31 or DONT GET a 3:31. It must be a BIG PINION 3:31
3:31s will limit your top speed by approximately 8%.
3:31s will SOTP feel like about 40HP.
But I stand by my 3.55 advice unless you have 525HP +
You said earlier this car was 'Street only' so why does 185 mph matter? If it does, then stay w/ 3.07, and hope for a Looooong vacant straightaway with no wildlife.
Commercial:
PartsRack carries Large-Pinion 3.33 in cryo-hardened, polished gearsets, complete with pre-calibrated speedo box and 'normal' pumpkin wear internals and new shaft-straps. Way under $650 for VCA members. 3.45, 3:54/3:55, 3.73, and YIKES 4:10.
Please call?!