Hi,
Not just the 18" front wheel ... the T100S model code, originally a 3-British-gallon tank (it actually holds a bit more than three gallons

) with only one outlet, the correct tap's an odd one, with two plungers - one for main, the other for reserve - your bike was also fitted originally with a skinnier rear rim and tyre than US-market bikes.
By-and-large, "H65573" onwards applies to your bike (H65573 is the first '69 500, Triumph swapped to the two-letter date code VIN format about three months after the start of the '69 model year). The only major differences are:-
. Your bike's engine's crankcase vents through the primary case, the cast 'elbow' bolted to the inner face of the primary and the hose secured around the edge of the rear fender. The change first appeared on late-'69 engines but isn't shown 'til the '70 parts books.
. Your bike's frame (plus components that attach to it) is/are basically H49833 ('67 model year) onwards ... except forks and front brake are also H65573-/'69-on; rear wheel should be '70-onwards (KD27850 is the first '70 500) .
. Your bike's exact electrics were only fitted in '69 (H65573) and '70 (KD27850); the workshop manual electrics addenda (HH at the end of Section H) includes two wiring diagrams for each model year, one each labelled "UK", the other "USA". When you have to look closely at electrics, the only actual difference between the "UK" and "USA" diagrams is the connection of the lighting lever switch supply wire on the back of the ignition switch ...
Nevertheless, when working on the bike, be aware of two linked things that can screw up that neat(?) categorisation ... Screw Threads And Wrench Sizes ...
Historically, before '67, Triumph used British Standard threads and wrench sizes (that Americans call "Whitworth"

); '67-on, Triumph
started to change to Unified/UTS threads and AF wrenches, but they didn't do all the fasteners in one go and, on the C-range, some were never changed before the last in '74.
However, as your bike is a '70, it might 🤞 not be an issue ...:-
. the 3/8"-diameter studs and bolts through the cylinder head (including four also through the rocker-boxes) are 3/8"-26 British Standard Cycle (BSC) thread, but 19/32" AF wrenches/sockets fits closely on their hexs.;
. the '70 parts books say the rear wheel fasteners were changed to UNF and UNEF threads/AF wrench sizes;
. almost all other threads 1/4" diameter (7/16" AF) and larger
should be UNC/UNF/UNEF with AF hexs. but, as I say, just be aware, if you do find an odd hex. size/thread, it isn't necessarily 'wrong'; always feel free to post a question on the Forum.
Otoh, threads smaller than 1/4" diameter
are a mixture ...:-
. the common one is 2BA (#2 British Association) - it's
very similar to both 10-32 (#10 UNF) and M5, but smaller than both, nor exactly the same pitch as either ...
. otoh, e.g. the screws that secure the 'gauze' to the front brake scoop are 4-40 (#4 UNC) and not what it says in any parts book ...
Note I've always referred to the "model year" above - that's what the "D" in your bike's VIN actually means, although neither Triumph manuals nor later books makes that absolutely clear.
Then, just to mess with your head, your bike was actually built in October 1969 ...
As vehicle-making companies still do today, Triumph started making "next year's" models part-way through the previous actual (aka "calendar") year. Reasons were: they were exported by sea, most of Triumph's output went to the US; so exports to southern hemisphere countries would arrive in their summer, it took several months to build up a stockpile in the US ready for their summer.
So although the "D" in your bike's VIN indicates the '70 "model year", because the "N" indicates October, your bike was built in "calendar" October 1969 ...
+1.
+1, plenty of it (although I've always used just bog-standard grease).
Yes. You have two long-time Canadian Triumph parts suppliers -
BCS (British Cycle Supply) and
Walridge - and several in the US.
Hth.
Regards,