The water pump bolts are sae.....they go directly into the block. Well, at least on my 454.
This is where it gets a bit strange. Haynes manual says '14mm' and sure enough when I had the pump on and off, a 14mm socket fitted perfectly. But is the thread metric? You say it isn't (I'm not arguing with you!) but odd for Haynes (or anybody) to quote bolt head size in different units from thread size. (Not that it matters for that, but for other bolts it's confusing).
The battery hold down bolt is metric, but the bolts for the side terminal battery are 3/8" coarse threads (also called USS). Most of the external engine fasteners are metric, except for the starter mounting bolts and the terminals. Most of the body stuff is also metric. On my trucks (I've had 2 99 Suburbans and still have 1) I've found that a lot of the things that I'm fixing can be done with a few wrenches and sockets. If you have an assortment from 6mm to 15mm that should do a lot of the basics. The Allen wrench for the brake calipers bolts is 3/8". Also the water pump mounting bolts are 14mm or 9/16"( can't remember for sure, but l think l used both sizes the last time I replaced it). The lug nuts should be 22mm if it's a 1500. Good luck with your truck! The brake pads replacement shouldn't take too long unless something doesn't come apart quickly, it's a fairly easy job.
Allen wrench being 3/8'' explains why 10mm is too big, 9mm too small. These little niggles!
Lug nuts (I have C2500) are 19mm across the flats but probably not original as chromed and truck has aftermarket (Eagle?) alloy wheels.
Pads only needed disturbing as I'm working on wheel bearings which are a bit ragged but will do for now. Do you buy bearings from dealers or bearing suppliers? If the latter, are they sized in imperial - they are odd sizes in metric (26, 41, 63, 74mm). Supply in UK is what I'm trying to get on top of here.
Am I right in thinking the front brake disc (rotor?) and hub (the part that carries the outer bearings) are in one piece?
Agreed, a fairly basic set of tools is all that's needed to work on this truck and it is pretty simple to work on - compared to the crampedness of cars at least. The thread stuff I need to research. The similarity/difference between UNC / UNF (British) and SAE etc. The info is on the 'net, just a case of when I find the time.
Thanks for the help and input here - much appreciated. The Suburban I've got hold of is in amazing condition - no corrosion anywhere and interior is immaculate. On top of that it's only done 42,000 miles. To find that in the UK is a surprise. It is also LPG enabled - a boon given UK fuel prices. If anyone else is running a Vortec 350 on it, I'm interested to hear more.
A few niggles here and there that I'm trying to get on top of (hence all the questions!) and when that's done I'll have a bit more time to have a look on this forum to see what you guys are running and generally get to know more about these trucks. From the very little driving of my Suburban so far (75 miles) I already like it - loads!