At 04:22 PM 5/16/05 -0700, Jim Paul wrote:
".... about the Lucas reverse lamp for MGA. I finally found one with an original MGA bracket which attaches between the inner rear bumper-spring and bumper, through the right center bolt. Looks a little big but it definitely fits perfectly".

Back-up lights on autos were not mandatory until the late sixties in the US, so none of the MGAs (or early MGBs) ever had them as standard. If you wanted a back-up lamp you had to have the dealer install it. For the British cars, Lucas sold the L494 lamp, a monster of an accessory -- about as big as a fog lamp but a little more "formal" looking. They were sold for Rolls-Royce, Jaguars, Healeys, Morgans, MGs and even Vespa scooters (as a headlamp!).

For the MGA, there was a mounting bracket that was slightly fluted to match the inside of the rear bumper, where it fit between the inner bumper spring and the inside of the bumper, fastened by the right middle bolt.

There was a matching Lucas pull-switch (#31696), similar to the black knob pull-switches of the time and the ones found on the MGA dash, with a little illuminated white dot in the center to let you know that the reverse lamp was "on."

I installed this knob between the tachometer and speedo, where the panel light rheostat knob was originally. I never used that control and merely disconnected the rheostat and taped the wires together. The hole in the dash is a tad larger than the shaft for the new switch so there is no need to drill out the opening, and it fits OK without wobbling. I think it looks perfectly at home with the other controls.

Note there are at least two styles of clear lens for the L494 lamps, the vertical ribbed lens and the crosshatch pattern. Most of the replacement lenses you can get are ribbed...the crosshatch design is a bit more rare.

I fitted a halogen bulb inside the lamp and noticed there was quite a bit of room left over, so I got the idea of having this lamp do double-duty as both a back-up light and a third brake light. A trip to my local electronics store yielded eight red LEDs, two dropping resistors and a small PC board to mount them. All of this fits into the right-hand side of the lamp, and since the LEDs are clear when "off," almost undetectable until they are activated. I attached their lead to the brake light wire in the rear harness, now the eight (fairly bright) red LEDs light up with the other two brake lights for safer freeway driving. [Okay, this last step was incidental}.

Much thanks to Jim Paul for this article and pictures.

Here we have a variety of rear lamps, all Lucas 494 type but with different part numbers. The first three have the early issue cross hatch lens pattern. The fourth with red lens has the later vertical rib pattern. The red lens was required as a rear fog lamp in some European countries. In that case the car might have a red lens fog lamp on one side and a clear lens reversing lamp on the other side.

The first lamp on left above, Part Number 058721, has the larger hollow stud where the wire runs though the mounting bolt. The included instructions are dated Feb.1958. This can be mounted on an original front fog lamp bracket (although some recent replacement brackets are poor shape and do not fit properly around the overrider). The second lamp in the first photo shows the cross hatch lens but with a solid mounting bolt and the wire exiting the rear of the chrome light casing. This would require a thin wall bushing for mounting with the factory type fog lamp bracket. This box is dated July 1967, and it is now marketed as an Accessory under Part No. 54057125.

The first box in the second photo is dated March 1961, so it appears that the cross hatch lens is correct for all MGA. The last two lamps have the larger hollow mounting stud and the connecting wire comes out the through the stud.

Addendum August 19, 2017:
Photos of a New Old Stock 494 lamp courtesy of Thomas Aczel in Australia.