D1 and D2 type bulbs operate at high temperature with great pressure probably near or over 30 atmospheres. The internal quartz arc tube temperature is probably typically around 800 degrees C (1400-1500F).. The outer bulb is not this hot, but it is definitely burning hot.
You may be able to find a kit with HID bulbs that are plug'n'play for 7440 bulb socket, I don't know, I didn't check, but if you plan to use D2S (or D2R or D2C) bulbs like I did, keep reading below. 5) The D2S bulb collar is slightly larger than the opening for the 7440 bulb in the tail, but not by much.
Duramax driver side dipstick
Dibels progress monitoring
Newmar depreciation