70 series owner since 2003
First and foremost, 'get the latest manufacture part that fits' versus trying to find the March 1988 BJ71 specific part. Remember also the 70 series chassis has run from 1984 production to today. A 1984 door will fit a 2022 truck and vice versa.
As rosco said above, engines pre 1994 are becoming harder to get (orange block 13bt, blue block 13bt, 3B, 3Bii, 1PZ, 2H, 12ht, 2F, 3F)
Over the counter parts from dealers can really be hit or miss. Many items are in the system from mine use in Canada and are warehoused in Ontario California at the main north american site BUT. More than a few of those require a willing dealer or contact ala Onur to place an order with correct importation paperwork to release those parts. I typically run a part number through google and find if several US dealer sites list it, I can see if open or locked status. My local Tucson dealers are worthless.
There are many UAE dealers who can also ship to US
Burjauto, Toyotadxb, Amayama, and partsouq. But I can't get them to ship many electrical wire parts, and I have received vent door glass but nothing larger. I have spent >$10,000 since 2012 and had $60 small parts and $1,600 transfer cases shipped.
www.online-teile.com has parts but won't ship to US. I have routed things through european folks to come to here.
I have not had success with Australian dealers since 2006 (Sydney City). Shipping is stupid expensive.
In the past, Cruiserparts has had some good stuff in New Hampshire (new or take off) but their shipping packaging are atrocious.
Marc and Penny in Canada also have take off stuff.
Dave Stedman is indispensable as a source for some things (thanks Dave!).
Mark Koback at Ens industrial parts also has things stocked for an emergency and can ship fast. (needed a 24v heater blower resistor and sent them asap when 3 channels failed in summer)
Used parts there are many like John at Radd Cruisers and Joekatana etc who have been soul savors.
And 4wheel auto, Cruiser Outfitters, Georg at Valley hybrids and Radd can get those new kits that keep things rolling.