Here is a pretty good writeup on gauges and he covers the transmission
temp pickup nicely, you may like what he did.
http://www.turbodieselregister.com/f...d.php?t=142109
On the boost bolt, the one I read about breaking said it was made from white metal.
A solid brass one like from Geno's should be fine. Always use a torque wrench.
About the manifold , where I tapped, between 3 & 4 cylinders it looked to be
between 1/4" and 5/16" thick, lots of metal. Before you start, make sure you
have a pencil sized magnet that will go thru the hole and reach to the bottom
of the manifold to pick up the shavings. My shavings were wet and gookie as
I used WD40 to lube the drill and tap. With mine I stopped turning the tap
about 3 threads from the top of the tap, 4 thds. maybe would be better.
larry