Help with stock Air Box I.D.

[cycleranger]

Can anyone give me a positive ID as to what year this air box is from?
The drawings in the parts list are so poor I can only narrow it down to maybe '74?
Thanks,

 

[Downeaster]

Can't say if it goes back as far as the TX, but it's identical to the ones on my '79 Special.

 

[cycleranger]

Really? The photos I've found of '79 air boxes look different.
It seems like Yamaha changed them slightly almost every year so I'm looking for confirmation. Thanks!

The drawings in the Yamaha parts lists are so poor it's hard to tell.

 

[5twins]

I think what changed mostly was providing an attachment point for the engine breather hoses on later boxes. If you don't have that then that probably is an early box. Here's a diagram for the '76 and later boxes. They have a metal pipe near the carb connection for the breather hose to attach to .....

http://www.boats.net/parts/search/Yamaha/Motorcycle/1977/XS650D/INTAKE XS650D/parts.html

 

[Downeaster]

Oops. Missed that. You're right, there are nipples on my boxes for the breather tubes.

 

[cycleranger]

I think what changed mostly was providing an attachment point for the engine breather hoses on later boxes. If you don't have that then that probably is an early box. Here's a diagram for the '76 and later boxes. They have a metal pipe near the carb connection for the breather hose to attach to .....

http://www.boats.net/parts/search/Yamaha/Motorcycle/1977/XS650D/INTAKE XS650D/parts.html

There's no connection for the breather hose on these air boxes.
Hopefully someone here can tell me for sure what year they are from.
Thx.