Dude, are you sure you owning YJ?
CDL is central locking differental. AWD is all-wheel-drive and 4WD is 4-wheel drive.
AWD is what Subaru got
full-time-4WD is what Rovers got - meaning that vehicle would try to drive with all wheels engaged but will transfer more power to the one that spins faster. So if your wheel stuck in huge mud hole - open full-time-4WD is more like one-wheel drive. And that wheel stuck in that hole.
CDL is central locking device that designed to split power equally between front and rear, giving it approximately 50/50 split. So if your rear wheel is spinning freely, your front wheels still would have power to get you out. Locking 4WD is what most offroaders like to use.
Advantages of fulltime4WD and AWD is that you not getting wiggling tail on gravel-like road or snow as rear wheel 2WD will get. Its more stable and gives you that fuzzy warm feeling of sequirity.
Now, models of Rovers that younger than 99-00 (was it there on original D2?) got special thingy called ETC that basically is electronically engaging brakes that sppse to block your wheels from spinning freely and thus giving some power to wheels that actually got traction. While nice and thoughtless this system is not really controlled by human (me not like that!) and also eats through brake pads like hungry kid eats burger
Entire point of ETC introduction was b/c too many mall mums and prestige buyers didnt know what CDL is designed for and where engaging it on the non-slippery surfaces, damaging drivetrain.
from 2004 (if i am not mistaked) LR reintroduced CDL on Discoveries, but they also coming with ETC.
Now of stuff on vehicle (Mike may told you that already, but..)
- CD changers (OEM) are very expensive for LRs. And i mean - very. 400-600$ for new ones to my recollection and pretty pointless. For 99$ you can get Duraband changed with MP3 playback for 10 disks. While its not so nobby looking - it makes its job and would keep you listening for stuff for about 6x10 hours of mp3s
- Vibes - those can be sign of few things - unbalanced tires, motor mounts and other ****. But more often than not - its rotoflex in rear driveshaft wearing out and cracking or U-joints on front shaft are about to ***** it. Replacement of rotoflex is like 80$ in parts or <400$ for replacement U-jointed shaft. U-joints on front shaft wears from hit and you either can replace them alone or swap entire shaft. If you dont do that timely - it can blow off and take part of transmission box with it, if happens at highway speed.
However - after accident with bent frame, and for that price, I would stay away from it. While Discos are very sturdy horses but frame damage is frame damage. Never trust restored frame, specially if you going to offroad it, IMHO.
