Aloha,
Here is an excerpt from the TRA (triumph Registry of America)Judging Standards & Restoration Guidelines 2004:
“Rear Bulkhead Panel (Front Petrol Tank Casing) - Several types of rear bulkhead panels were fitted to the
cars during the production run. These are described below.
TS 1 through TS 8636 were fitted with a lightweight fiberboard panel trimmed in unpadded vinyl to match the
trim color of the car. These panels had no piping, sewn pleats, or pressed in "pleat" designs.
TS 8637 through TS 22013 were fitted with three types of rear bulkhead panels.
- Early (?): Some early TR3's were fitted with an untrimmed "pebblegrain" millboard that was either
black or sprayed to match the trim. These panels had pressed in "pleats" in the pattern illustrated
below, courtesy of The Roadster Factory.
- Late: At some point unknown, the untrimmed panel was replaced by a trimmed panel identical to the
TR2 panel above, except the fiberboard may have been a little more substantial.
- On TR3's equipped with occasional rear seats, the rear bulkhead panels above were replaced by a
wooden squab board upholstered to match the front seats and rear cushion in either vinyl or leather
and vinyl. The sewn pleats in these squab boards were similar to the pressed in "pleats" of the
untrimmed "early" rear bulkhead panels.
TS 22014 through TS 60000 were fitted with two types of rear bulkhead panels.
- Early: The early TR3A's were fitted with a rear bulkhead panel made of two parts, a plywood lower
panel and a steel upper panel. The two panels were rivetted together, then trimmed in vinyl of a new
pattern of horizontal pleats. The edges of the panel were piped in contrasting colors (usually white or
cream). These panels were rather heavily padded with cotton wadding, as there was no squab board
with TR3A occasional rear seat assemblies. This panel is illustrated below, courtesy of The Roadster
Factory.
- At some point in 1958, the two piece rear bulkhead panel was replaced by a one piece rigid fiberboard
panel trimmed in padded vinyl of the same pattern as the two piece one. The sewn pleats were also
replaced by pressed in "pleats" at some point, most likely at or around the same time, as the one piece
rear bulkhead panels observed all had heat pressed "pleats".
- At TS 60000, the lower portion of the rear bulkhead panel was altered to fit the new flat rear shelf.
Otherwise the construction and trim of these panels was the same as those immediately preceding.”