Scott, is this the right series?
Mechanical:
3351 - Trans. Temp. 140°-280°F (8 ft. tubing)
Above temperature gauges include a 1/2" NPT fitting and capillary tubing (length noted by description).
Electrical:
3357 - Transmission Temp 100°-250°F
Includes 1/8" electric sender, 3/8" & 1/2" NPT fittings. (Not Shown)
Should I go electrical?
And then you just used green bulb covers for the green needles?