Tacho (Modified from original, no identification on the terminals) and Fuseable link questions

Just putting an ez wring loom in my LC and have a few questions:

1. In the GTR dash, previous owner has modified the tach from original. It has no identification on the two terminals, so i'm not sure if it is a 2 wire or 3 wire tacho (as it may be earthed under the silicon that i cant see). Is there any way to test which terminal is which with a multimeter or other method? If i just wing it and get it wrong, will it kill the tacho?

2. How important is the fuseable link between the starter and the ammeter? Also can a blade or glass fuse be used to replace the fusable link, and what size fuse will i need?

3. Can you buy the replacement metal spade clip inserts for the multiwire connector for the light switch and other multi connects?

Cheers
Ben

With the tacho, if you see multiple connections on the PCB to one of the terminals, then that one is likely to be the earth. The fusable link can be deleted, i did it in a few of my vehicles. I have bought the replacement blade clips from my local sparky.

Thanks chopper, unfortunately can't see the back of the PCB as it is all caked with a retarded amount of silicon. I assume it is broken as it wasn't connected with the previous dodgy loom, suppose i'll follow the below tests to see if it works or to scrap it.
1. i'll take a guess and connect one wire running from-ve side of coil to one of the terminals and connect the second to earth.
2. If that doesn't work I'll swap the wires.
3. If it still doesn't work remove the earth and supply +12v
4. If that doesn't work I'll swap the wires.
5. Bin job, previous owner already butchered the housing so will just fit an autometer unit

Can anyone advise what size blade fuse i would need to replace the fusable link?

Just keep in mind, a fusible link is a "slow blow" item basically, and a normal fuse will blow instantly where the fusible link can handle brief current spikes ok. I know people do remove them and fit with fuses in some cases, but personally I tend to just replace them with a new fusible link if needed..

(I used a factory late model GM one on my swap actually)