Four Wheeler - - Techline -

QI love the mag, the on­line ar­ti­cles, and so on. Thank you! I de­cided to mall-crawl my ’68 half-cab Bronco that I orig­i­nally in­tended to build as a crawler. Early Bron­cos are be­com­ing too valu­able for me to feel good about beat­ing it to death. This left me with noth­ing to wheel. Since that wasn’t go­ing to work, I re­cently picked up a ’83 CJ-7 roller with a 383ci stro­ker GM V-8, mil­i­tary king­pin Dana 60 front axle, and a 14-bolt rear axle with a Detroit Locker. Both axles have 4.56:1 ra­tio gears. The trans­mis­sion is a T-19 man­ual and the trans­fer case is a Dana 300. It also came with some ex­tras like a Blue Torch Fab­works full width kit on the front, some Poi­son Spy­der rock slid­ers, and so on, but, it’s ba­si­cally trash oth­er­wise. The mo­tor and driv­e­train are not in­stalled and the tub and frame are Swiss cheese.

To solve this prob­lem, I picked up a buddy’s ’85 CJ that is in much bet­ter shape to swap all the good­ies into. I’ll be swap­ping things over one ma­jor com­po­nent at a time, start­ing with the axles and driv­e­train. I plan on build­ing a crawler first and fore­most, with (very far into the fu­ture) dreams of Moab, Fordyce, and the Ru­bi­con.

As­sum­ing I go with the

383 Chevy V-8 as my pow­er­plant, should I stick with the T-19 and Dana 300 or go with the NP435 and NP205 that I orig­i­nally bought for the Bronco? I know I’ll need a Chevy NP205, but that’s not a deal breaker. I’m more wor­ried about over­all dif­fi­culty of the swap, clock­ing of the NP205, weight, and just fit­ting it all in nicely.

Yes, there are a mil­lion threads on the T-19 ver­sus the NP435 and the Dana 300 ver­sus the NP205, but I’d rather get an an­swer from true ex­perts that I can trust. My NP435 and NP205 have the lower spline count on the shafts, so they are not as de­sir­able, but I’m OK with up­grad­ing those if need be. I’m aware of the SM420, but I can’t find one. What say you? All ad­vice and opin­ions are ap­pre­ci­ated.


AA lot of the driv­e­train de­ci­sions you need to make will be based on tire size and driv­ing style. The Dana 300 is a great com­pact trans­fer case that will typ­i­cally al­low you to re­tain the fac­tory CJ-7 wheel­base, if that’s the plan. Given that you in­tend to run a 1-ton Dana 60 front axle and a 14-bolt rear axle, it’s likely safe for me to as­sume that you plan to run tires that are at least 37 inches tall and pos­si­bly much larger. With the power of the 383 V-8, over­all weight, di­rect drive of a low-geared man­ual trans­mis­sion, and the as­sump­tion of tires larger than 35 inches, I’d be a lit­tle ner­vous about us­ing the Dana 300 trans­fer case. Could you make it work? Of course, but it will re­quire sane driv­ing and proper drive­shaft an­gles that don’t al­low bind­ing un­der load or when the sus­pen­sion cy­cles. This can be tricky, es­pe­cially with the axlewrap that leaf springs usu­ally al­low.

The Dana 300 front and rear out­puts are usu­ally the first to fail on a build like this and it’s typ­i­cally be­cause of drive­shaft bind­ing. If you are care­less with your drive­shaft an­gles and driv­ing habits, I’d rec­om­mend in­stalling heavy-duty 32-spline out­puts front and rear on the Dana 300 right away. JB Con­ver­sions (jb­con­ver­sions. com) of­fers front and rear 32-spline out­puts. Ad­vance Adapters (ad­vanceadapters.com) and No­vak Con­ver­sions (no­vak-adapt.com) both of­fer a heavy-duty 32-spline rear out­put for the Dana 300. Be sure to check the Dana 300 model be­fore or­der­ing parts. There are two ver­sions that came in Jeeps and one In­ter­na­tional Har­vester ver­sion. The less com­mon ’80 Jeep Dana 300 can be iden­ti­fied by a shorter rear out­put hous­ing assem­bly that mea­sures in at about 3.5 inches. The ’81-’86, and most com­mon Jeep Dana 300, has a rear out­put assem­bly that mea­sures in at about 5.5 inches. The In­ter­na­tional Har­vester ver­sion of the Dana 300 has a Tex­as­shaped mount­ing sur­face (sim­i­lar to the Dana 20 and Spicer 18) in­stead of the round mount- ing face found on the Jeep Dana 300. Not all parts will in­ter­change, so or­der your af­ter­mar­ket out­puts care­fully.

The NP205 is an ex­tremely heavy-duty trans­fer case that is more up to the strength level of your other driv­e­train com­po­nents than the Dana 300. How­ever, it’s very large and will likely re­quire that you ex­tend the wheel­base of your CJ-7 to have proper func­tional sus­pen­sion move­ment and drive­shaft an­gles. The only ma­jor down­fall of the NP205 is the pa­thetic 1.96:1 low-range gear. This makes the NP205 less de­sir­able for a 4x4 that you plan to do any kind of slow tech­ni­cal rock work with. Of course, there are so­lu­tions. Of­froad De­sign (of­froad­de­sign.com) of­fers sev­eral dif­fer­ent crawl boxes that can be added in front of your NP205 to get the gear­ing down lower. You’ll likely need to ex­tend the wheel­base of your Jeep sev­eral inches to al­low for the added length of an Of­froad De­sign Dou­bler or Mag­num un­der­drive unit. If you only want to ex­tend the wheel­base a few inches, JB Con­ver­sions of­fers the Lo­max kit to con­vert your NP205 to have a 3:1 lowrange gear. This setup would keep the NP205 trans­fer case at its fac­tory length.

As for the trans­mis­sion, the T-19 and NP435 are both great. Their adapt­abil­ity will de­pend on what they orig­i­nally came out of. I think you could sim­plify your swap and re­duce costs sig­nif­i­cantly by stick­ing with a GM man­ual trans­mis­sion, es­pe­cially if you plan to run the GM NP205 trans­fer case. The SM420 and parts for it are get­ting harder to find, so it’s not the best choice. You might want to con­sider the GM SM465. It came mated to the NP205 from the fac­tory. If you can find this combo used you’ll save a lot of money on adapters and it will bolt right up to your GM en­gine with a fac­tory bell­hous­ing. Ul­ti­mately, try­ing to adapt your Ford trans­mis­sions to your GM mo­tor and trans­fer case isn’t all that cost ef­fec­tive. Just be­cause you al­ready have the com­po­nents doesn’t nec­es­sar­ily make them an ideal swap. If you de­cide to keep the Dana 300, just run the T-19 that it’s al­ready mated to. Make sure it’s a T-19 and not a T-18 be­fore or­der­ing any parts.

Nor­mally, you should mock up the axles first with what­ever wheel­base that you have planned for your project. How­ever, in your case, I think you will want to mock the en­gine, trans­mis­sion, trans­fer case, and any crawl boxes into place be­fore set­tling on a wheel­base. It will take some trial and er­ror and you will likely have to move things around a few times to make it all work prop­erly. Don’t for­get to take the ra­di­a­tor, fan, ex­haust, drive­shaft clear­ance and an­gles, steer­ing, and so on into con­sid­er­a­tion be­fore fi­nal weld­ing of all of the en­gine and sus­pen-

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