Need np203 advice

[zac]

I hate to rehash all this again, and I have done alot of reading here about this, just want to make sure I have it straight and know all the options. I grew up driving 203 equipped Chevs, that's just what 4wd was to me. Ever since then though I have had 465/205 trucks. So I bought a '79 K20 over a year ago with a th400/203 combo and full floater. I use it as a rarely-driven work truck, and my wife drives it some with the kids, so I wanted three people to be able to ride in relative comfort. So no 4spd. But needless to say, I am not enjoying full-time 4wd like I used to. I'm thinking about putting in a part time kit. So there are two kits available, correct? The cheap Mile Marker kit, and the more expensive one with the shaft, right? What's your preference? Also, what about the oiling issue? I've read that with both these kits you have to make sure to lock it up every couple hundred miles. But I've also seen people claim that's not necessary, depending on the year of your case and the kit you use. So what's the deal?

Also, I recently bought a set of new condition 31x10.50x16.5 tires to put on my 8.25 steelies. Don't know how long it's been since those were made. Problem: they are from two different manufacturers, they look to be the same height but I know better. So is running these tires going to kill the differential in my case, or just make my mileage even worse? Or both? Again, this truck doesn't get driven much, maybe 2000 miles max in the last year.

I'm tempted to scrounge up a 205, but I want to keep the th400 and I know the $$$ situation on those cases. It hardly seems worth the effort and money for this truck, especially since the average price for a 203 in my area is $50-$75.

Any input is appreciated.