ammeter blowing fuses/ getting hot

your ammeter is bolted into the dash pod/ frame by the 2 bolts that are the main electrical connections to the meter
these bolts/connections are threded rod with a sandwich of insulation, 2 or 3 nuts and some washers

the ammeter connectors and the nuts used need to be totally insulated from the dash pod/frame
this is done with fibre washers either side of the dash pod between it and the nuts that are used to possition the gauge and hold it in place
1 side has a plastic washer that is like a top hat that sleeves the stud... the top hat section slips down the hole in the pod to stop the threaded section shorting to the inner diameter of the hole

if the ammeter has ever been over heated this insulation fails and causes a direct short of battery to body

to fix
take out dash pod
remove ammeter gauge from it

replace all insulation with new fibre washers and lengths of thin plastic tube made from something that is high melting point. electronics stores have just the thing for insulating the tabs on power transistors etc find somthing that sleeves the studs and provides a washer section to keep the nuts form hitting the pod

bolt it back into the pod and check with your multimeter set to continuity that there is no beep or that there is infinite resistance between the case and each stud

this seems to fix many "broken" ammeters. they aint broken its just the insulation went hard and crumbled or melted..

with an properly insulated gauge if the fuse stil pops your issue is a short in another cable
potentially the main feed pin in the bulkhead connector has shorted to a neighbour.
drill right through and push a fat insulated wire through and basically bypass the bullet connector that is causing the problem by connecting the orginal wires to either end (suggest solder and shrink sleeving would do the job) its a bodge but it works

Dave