depends on your intended use of the jeep. as joe said,you wont be able to use 4wd on pavement any more,so if your truck is a daily driver that sees alot of snow/ice/or other inclimate weather useage,it meybe worthwhile to have a 229 profesionally rebuilt,or at least buy one thats in good working condition. keep it full,and change the fluid regularly.there are alot of folks with properly working 229s that are happy with them,and in all fairness,prolly alot of failures are due to neglect and improper mantenance.
having said that,the 229 is useless for off road use.the low range is locked like a conventional part time xfer,but the full time high range makes limping home on the front shaft not an option if you have rear driveshaft trouble.unless of course,you live close enuff to the trails to get there in low range
the 208 is a much simpler design,and much less problematic.you will be eliminating the vaccum thingamajig that frequently give 229 users trouble. it is a completely bolt in swap.you will need a longer rear shaft(if the 208 comes from a chero or wag its rear one will work) and the shift linkage from the little flag lever to the xfer lever.
just about any NP case will swap.a nice one IMO for a street truck would be the 242 found in xj cherokees.it give you 2wd,locked 4hi,full time 4hi,and locked low range. it bolts right to the tranny,but shifter mode will be needed,and the rear driveshaft on an xj is a slip yoke,rather than a fixed yoke,yo yoll need a completely new driveshaft.
the 219 will fit also.it will directly replace the 229,use the same driveshafts,and will eliminate the vaccum thingamajig.the 219 is a nice case also,giving you a full time 4hi and a high lock.the only bad thing is no 2wd.
hope this helps.any other ques?
85 grand wagoneer
258 with motorcraft 2bbl/904/twin stick dana 300/dana 44/welded amc 20
38x15.5 gumbo mudders
snorkel/dual batteries/onboard air/"custom" convertable
3 inch body lift/mostly stock suspension/"modified" fender openings
custom front/rear bumpers and brushgaurd
T18/dana-spicer 18 with drum E brake and PTO swap very soon
searching for offset QT rear and PTO winch