Terrible rattle on start up.

[Buddy Holley]

Seems to be a rattle/knock on start up near the gearbox, then when its fired it goes away and oil light goes out.

[Charles H]

I.m with Johnnydog on this one. What oil filter type do you have? Original cartridge type or modern spin on? If the former try this https://www.chriswitor.com/proddetail.php?prod=CW2525

[Buddy Holley]

Yes I have the original oil filter casing on, that one that sticks out horizontally. i did buy a newer spin on filter which hangs down like the one in the link you sent me, I'll put this on. any ideas on torque settings or is it a case of nipping the oil casing up and then hand tighten the oil filter?

[Charles H]

As you say, just needs nipping up. Make sure you remove the old O ring in the block. Sometimes I have even seen two! Fit the new O ring into the block recess and 'stick' the larger one onto the adaptor with grease. Make sure the filter sticks down as far as possible. Usually easiest to fit the filter to the housing and bolt on the entire assembly.

[johnnydog]

It might be worth getting an assistant to use the stethoscope method (long screwdriver!) around various places in the area that you think the noise is coming from - people describe noises differently.
Has your Triumph always been a manual? Has it been converted from an auto in the past? Just a thought as you say the noise is towards the gearbox end - autos had a spacer shim between the starter and bellhousing, which isn't required with a manual. This would position the bendix on the starter in the wrong position, and it would not engage correctly with the ring gear, and may cause a noise similar to the one you describe when cranking. Easy enough to check if the spacer is / isn't there.