This thread is really nice , so much informative .

And finally I have got the answer to the reservoir tank of the Z432-R , the tank is exactly the same as our US and Canada early car except one tube is omitted by hand .

Pleae see the attached picture , you see the tube’s end is smashed , looks like heated by gun to melt the tube . I think we can say this tank is shared with our US and Canada tank , just one tube is different.

Not only this , the white  front window screen , the fuel door knob, also rear deck rubber mat , side sill rubber trims ( left side is a bit different due to a foot rest ) are shared with export cars and Z432-R . Some of the items also shared with a Fairlady-Z , S30S ( Z-std ) . 

BTW , this tank 17350-E7201 Tank-Reservoir Fuel 4.2L , 2000JPY is now on sale at Yahoo Japan auction. 

Kats

The 100l fuel tank does remind me of the SP/SR311 fuel tank, and its sport option larger version especially. Sports option on the left.

Differences, obviously, but the general shape is the similar.

 

I've seen the embossed "X" shape of the fuel tank sides rolled into other places:

 

 

 

I think they call it 'Informed Inspiration'. The 'Grünvogel' method of strengthening a flat panel - check out the Wehrmacht-Einheitskanister - must have been in engineering text books for the Japanese engineers. On a fuel container it certainly serves to reduce 'oil canning' whilst also allowing expansion and contraction without putting too much stress on the welded seams. A little bit of genius.

 

Bang on!