Desperatly need some np203 Mile Marker 501 kit part time install help - thanks

[74k20]

Dug thru all my old emails and pictures, and don't seem to have the thickness and Ø sizes written down anywhere.  Sorry but I'm not going to tear into this t-case again just to give you the dims   haha.  SURE wish you better luck then the fumbling I had to learn from.  Hope this simple write up will save you some headache.  Good luck.  YES this project was worth the hassle and not bad once over and know what to expect.  Bummer part, is that my t-case still leaks out the front and will either have to be taken apart to re-seal/rebuild, or find another case someday.  The 203 fits my needs just fine.

[mechanic58]

Thanks for the prompt reply - I certainly wouldn't expect you to take your 203 apart just to answer my question...lol. I did get more out of this thread on this topic than any other tidbit I could find online about this conversion. I still can't believe how vague the milemarker instructions were - wow. They really need to hire a good technical writer.

[mechanic58]

Ok - thought I'd update the thread with my findings. I took my 203 back apart today and spent some time taking some precise measurements. It's important to note that my 203 is an early model ('73) with the one-piece tail shaft housing and an 8-bolt diff. It uses the shouldered spacer that is mentioned in the milemarker 501 kit instructions. This spacer in original form is exactly 1/2" wide. I had to shorten it .050" on the thick shouldered end to make this kit work.

[74k20]

Are you installing the cast one-piece tail shaft housing with the t-case in the truck or out?  I did mine with it still in the truck.  IT'S HEAVY and hard to load correctly if so.  Keep us posted.

[mechanic58]

Are you installing the cast one-piece tail shaft housing with the t-case in the truck or out?  I did mine with it still in the truck.  IT'S HEAVY and hard to load correctly if so.  Keep us posted.

Um...yes. I been mechanic'in for nearly 30 years - I'm a tad manly. I really didn't think it was all that bad. I didn't have any issues.

The first time I had it apart it was on my bench top. However I wasn't satisfied with how I put it back together and I decided to take it back apart today. (It had not yet been run) After having read this thread since I first worked on it I decided it was assembled incorrectly - and it was. It's right, now. I have about .012" of end play on that shaft WITH the milemarker torrington bearing installed -which is just about perfect. Previously I had assembled it without using that torrington because it wouldn't fit (because the spacer in question was too thick). So what I did to make up for the excessive end play was to shim it on the back side to the tune of about .110". It worked - except when it was in 2HI the front drive cog was just barely raking the shift hub and it was making a grinding noise. I knew it wasn't right, obviously. It's fixed now though.

[werewolfx13]

I know who I'm gonna call if I need to take my 203 out again 

Course, when we put mine back in, I was dealing with an inflamed torn rotator cuff, and the guy helping me had rested his bare hand with all his weight on a glowing hot pile of cutting torch slag the night before, so it might have seemed SIGNIFICANTLY heavier than it really was...

[mechanic58]

lol...ya know, I have installed more than my share of these big-assed heavy transfer cases over the years. The first couple that I did were pure heck - I remember. However - in my wise old age I have finally discovered the easiest way to do this shoot...

The easiest way to install an NP203 is to also remove the transmission and bolt them together on the ground and install the entire chunk at one time - but the KEY to doing this is also removing the crossmember and bolting it to the transfer case mount - just like it would be if it were all installed in the vehicle. Then set the entire combo on a floor jack (jack pad right under the trans mount on the crossmember). With the torque converter removed, this will actually balance quite well on a jack in this configuration. I'd recommend using a small ratchet strap though, to kinda steady it on the jack. (if you can't figure this out, you probably shouldn't be messing with it anyway). Then you can roll the whole combo under the truck and just let the truck down on it (I have a two-posted lift in my shop).

Works good, no sweat. Didn't even get a blood blister.

[74k20]

I built/scabbed together a cradle, and tacked it to my floor jack.  Worked GREAT, until I realized it was too high to go under the truck.  But the floor jack was busy.  So I used my engine hoist on my front receiver hitch and lifted the front of the truck enough to slide tc/jack under it.  Worked great. 

Redneck - but worked. 

[mechanic58]

Your tires are on backwards!

[74k20]

You must be one of those "white letter out" kinda guy.  hahahaha

[mechanic58]

Have to dig this one up again. I have installed about 4 of these 501 kits over the years, both in the early and later style 203s...and I have had the exact same problems the OP is speaking of here. Everytime I have had to manufacture a proper spacer in order to get the kit installed 'correctly'. MileMarker doesn't supply near enough parts to do it correctly and the instructions that come with these kits aren't even good enough to wipe your  on. A good millwright can surely figure out how to get this installed correctly, but the average shadetree is going to get his  kicked by this kit for sure. I just wonder how many 203s have met their demise at the hands of an improperly installed MileMarker 501 part-time conversion kit? I bet a lot.

Edit: Posted in here again because I just got done struggling with another one of these MileMarker kits, this time in a '76 model box.