Hanzo:
Correct, the 03-06 ones will have the 6g75. How much initial work you decide to put in the car will depend on your risk tolerance. Some folks fix only what is clearly broken, others do a lot of preventative maintenance as a baseline (w/ high mileage multi-owner vehicles and missing/spotty service records this seems a safe course and one I subscribe to).
Main complexity w/ any head work on the 6g74 and 6g75 is that you must take off the intake plenum to get to them (and replace the relevant gasket). Here's a quick price list from RockAuto (personal preferences, not cheapest, I've had good luck w/ Fel-Pro, some of those are on closeout and cheaper than usual) as to what doing the stem seals would take (not incl. tax, shipping):
- Valve Stem Seals: FEL-PRO SS70795 {#B45870A} $20.99
- Valve Cover Gaskets and spark plug tube seals: FEL-PRO VS50461R {#MD303148, VS50270} PermaDry®; Set $29.79
- Intake Plenum gasket set: FEL-PRO MS96740 {#MS19532} $14.74
While working on the heads, I'd also clean the intake, throttle body, EGR valve (and replace the gasket too), and clean/replace valve lifters/lash adjusters (clean w/ diesel), examine/replace spark plugs, spark plug wires and boots, replace rear camshaft seals. Might be a good time to do a leak-down test at the same time (to estimate the condition of the bottom end).
Additional stuff I'd do as a baseline if maintenance history is unknown (in no particular order):
- Replace PCV valve
- Change oil, oil filter, drain plug, add oil catch can (guys in Aussie forums use them for Challengers (Montero Sports) and Pajeros (Monteros), less often seen in the US though)
- Intake air filter
- Transmission filter, gasket, flush (coolant line method; SPIII seems to work best; Mitsu, Hyundai, Kia, Eneos make it)
- Gear oil (transfer case, differentials)
- Brake flush (and check pads, rotors), check caliper pins (apply clean silicone paste, replace boots and pins if necessary), check caliper sliding surfaces (clean and apply brake grease as appropriate)
- Power steering flush, check tie rods, check rack and pinion (seals), check power steering pump (seals)
- Grease ball joints (replace or install grease fittings as necessary)
- Check wheel bearings
- Check shocks/struts (KYB Gas-a-justs are popular if replacing)
- Replace serpentine belt, adjust tensioner/idler pulley
- Check stabilizer bar bushings (I like using 303 to keep the rubber flexible, but that might be snake oil/placebo effect)
- Timing belt, water pump, tensioner
- Replace crankshaft bolt, washer if using old style
- Wheel rotation, balancing, alignment (303 is supposed to be good for sidewalls and dry rot, but I'm undecided about that)
- Flush coolant system, new coolant
- Clean battery terminals, check battery and cables
- Clean any easily-accessible electrical connections and grease w/ dielectric grease
A good way to find previous threads on the Gen 3 (the in-forum search feature doesn't work as well) is to search the site in Google w/: site:forum.expeditionportal.com/ (Montero OR Pajero) AND ("Gen 3" OR "Gen III")
Small world! The Niva was the first 4x4 I fell in love with in the 90s in Moscow
Soon followed by some UAZ 4x4 the army used (469 maybe?). Unfortunately neither have been imported in the US (although some Nivas were imported into Canada in the 80s and made their way to the US as grey imports).