A Forum member has 2 seats in his 69 and is seeking (as I am too ) some advice and knowledge from the wise amongst us. (permission granted to post his pictures)
The drivers seat appears to be a 300 but the passenger seat appears very deep in the bucket and Hi on the bolster. Both appear to have Scheel fabric and both are of fibreglass construction.
Pic's below.

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Underside of Drivers seat

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Underside of passenger seat

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Thanks in advance.