Replacement lamp for PT Surge?

I like running my Surge on Nimh batteries but it is noticably less bright then running the Surge on fresh alkalines. Is it safe and feasible to replace the stock Surge lamp with one of a lower voltage rating as to get the same brightness using nimh's as you would using alkalines with the stock lamp?

If so any recommendations? I have a spare bulb for the Surge and it says nothing about the voltage and amp ratings so I don't know where to begin. I don't even know what type those little bi pin bulbs are called but I know they're far less popular then the flange type at the local walmar/radio shack.

I'm told that the Surge bulb is a T-1 3/4 bulb. Brock's site http://www.uwgb.edu/nevermab/flash.htm

measures the running load on this bulb at 5.35 V and 1.1 A. Your NiMH's won't deliver more than 4.8 V for more than a very few minutes after charge.

I don't know who else makes or markets T- 1 3/4 bulbs. If hou find someone, be careful that both the wire lead spacing and the distance from the base of the bulb to the filament are the same. The T-1 3/4 designation only refers to the diameter of the clear bulb "envelope" be it glass or quartz.