What was the last year the metal gas tank was used in the bricktop ?

[nitehawk55]

I bought 2 new complete D series 501 engines a few years ago and they have the metal tank . I think they are 1971 and if I recall the plastic tanks were first used in 1973 or 4 ?

 

[Lawnboy77]

The parts breakdown is showing 1973 as the last year for the steel tank bricks.

 

[nitehawk55]

Thought it was 73 .
Thanks !