If your old Garrity 2D flashlight uses a standard PR flange-type bulb (has a wide flange with a notch in it), then there are a number of compatible LED replacements. Here are some examples:
TerraLUX TLE-1F - 40-50 lumens, 2-6 cells (3-9 volts), 1 watt cool white power LED (I think)
Nite Ize LRB-07-PR1W - ditto--seems rather similar to the TLE-1F with regard to specs and performance
Dorcy 41-1643 - 30 lumens (on fresh cells), 2 cells (3 volts), looks like an overgrown 10mm LED on steroids (apparently has six dies), not sensitive to polarity, quite efficient, inexpensive
The only one of these that I have any experience with is the Dorcy 41-1643--I picked one up for cheap at a hardware store, just for kicks. The tint of the beam is...interesting. :thinking: I want to say that it has a very high color temperature, almost violet, but it has some yellowish qualities as well (all pretty uniform, too). Despite this it's usable, works well with reflectors designed for PR bulbs (beams look the same but more uniform), and renders colors OK for a cool white LED and substantially better than a typical 5mm LED when I compare them side-by-side. The claim of 30 lumens seems accurate for fresh cells, although in my limited testing it doesn't decline a whole lot over the first 24 hours even in a 2xAA flashlight (longer in a 2xD flashlight), which means its efficiency is good even when compared to more sophisticated LED flashlights.