TR6 intake and exhaust ports change in 72

[Don Malling <dmallin@attglobal.net>]

I know the intake ports changed in 72. The two middle intake ports were 
closer together from 68-71 than they were from 72-74.

Did the exhaust ports also change? Maybe the 72 head was thicker for a 
lower compression ratio, so the exhaust ports sat a little higher with 
respect to the block?

The real question is whether the dual exhaust manifold from a 72-74 will 
fit a 68-71?

Don Malling