if you want to learn about VW diesels, there's no better place than vwdiesel.net unfortunately the registrations are closed ... I'm not a member myself.
Here's a brief overview of the engines:
1.5 normally aspirated indirect injection diesel - unless its a steal don't bother because they aren't great for turbo'ing since the blocks are poorly designed.
1.6 normally aspirated indirect injection diesel
1.6 turbo indirect injection diesel
1.9 normally aspirated indirect injection diesel - I think these were only in canada ...
All the above engines have minimal electronics. The fuel injection is strictly mechanical which is great for the DIY home mechanic.
1.9 turbo direct injection (aka TDI) - depending on what year you get, i believe anything model year 2000+ has an immobilizer and you'll have to pay to get a custom ECU program to defeat that. Unless you want to use a whole bunch of other electronics from the donor vehicle (cluster, ignition switch stuff I forget what else). These motors compared to the IDI tend to be a lot more expensive, and definitely have more wiring and whatnot.
I'm going to sell off my 95 passat VR6 and buy a 1991 jetta NA diesel sometime this month. Once I get used to the whole diesel thing then I'm gonna be looking to get a samurai or something to put it in.
as far as putting one in a suzuki I don't know crap. What I do know is all older VW 4cyls have the same transaxle mounting bolt patterns as well as engine mount bracket bolt patterns. So, presumably with an Acme kit you can stick any VW 4cyl from 1975-1999 and probably some later ones in your truck. There are some great gas engines at good prices with high availability and decent aftermarket support. e.g. the ubiquitous ABA 2.0 8v found in 1994-1999 vws has 115 hp and 122 ft/lbs which can be had for dirt cheap.