HID Lighting Questions

Some questions on HID lighting. I have a 1974 PA28-151 and would like
to replace my landing light (cowl mounted) with an HID light. I know
about the boom beams, but I also see that Precise Flight makes HID
lighting also, and it's about half the price of LoPresti's.

I looked at Precise Flight's installation manual and noticed that it
was written by Knots2U. In addition, it states that the lighting is
for wing mounting only and for Piper models PA24/30/39 aircraft.

My question is... a PAR36 bulb is a bulb is a bulb, isn't it? Aside
from perhaps the legality of the FAA approving this STC for one
specific location, wouldn't this bulb and installation kit work just
as well for a cowl-mounted light? The specifications for this bulb are
exactly the same specs as for all of the other HID bulbs, i.e. 500,000
CP, 35 watts, 12 volts, 2.5 Amps, PAR36, etc.

Steve
KDMW