Tranny skid
With a 1-1/4" body lift (BL) and a 1" motor mount lift (MML) in place, it's time to do a partial tummy tuck. Under Cover Fabworks (UCF) makes tranny skids in three different depths: "No Body Lift", "Extra Clearance", and "Ultra High Clearance". And you can order steel or aluminum, in two thicknesses. I bought the Extra Clearance skid in 3/8" aluminum, along with an aluminum engine skid. Expensive, yes. Buy once, cry once. A Black Friday 15% discount eased the pain a little.
The 2005 OEM "shovel" is 4-1/2" deep on the outside, and 3-5/8" deep inside (mounting flange down to where the tranny mount sits), and weighs 42 pounds. The UCF Extra Clearance skid is 2-3/8" deep on the outside, and 1-1/4" deep inside, and weighs 38 pounds (this is the "thick" 3/8" aluminum one).
So ground clearance will increase by 2-1/8". But the tranny will move up 2-3/8", increasing driveline angles accordingly. Since I have a 2-1/2" spring & spacer lift, it will be an effective driveline lift of 4-7/8". I'm keeping the OEM tranny mount because I don't want the extra vibrations from a UCF LOPRO mount.
Installing the new skid is quick and easy. Support the tranny, remove 6 bolts and 4 nuts, drop the OEM skid, lift the new skid, install the bolts and nuts. If only that was all there was to it.
With the new skid holding the transmission higher, the fan rubs firmly on the bottom of the shroud. I removed the fan, and the shroud, and drilled new holes in the shroud to lower it by about 1/2". I also had to trim away some extra plastic to make room for the bolts and washers.
With an effective 4-7/8" driveline lift, this LJ had driveline vibrations pretty bad. I had expected that, but I also had expected to be able to add a skid spacer to eliminate the vibes until a later date. After spending more time and money making custom aluminum 1/2" spacers, and then increasing the skid plate drop to 1" by adding more 1/2" spacers, the vibes were reduced but still there.
Adjustable upper rear control arms
There was a 4° mismatch between the rear pinion and the tranny shaft angles. The original two-U-joint driveshaft is still in place. I installed Savvy double-adjustable upper rear control arms, and tilted the pinion down to match the tranny shaft. This matches the U-joint angles, but increases the angles of both U-joints to 13°. According to Tom and Shawn Wood, this is pushing the limits, but sometimes works. In this case, vibrations were reduced again, but still present.
To confirm where the vibrations I was hearing and feeling were coming from, I removed the rear driveshaft and drove it in front wheel drive. It was very noticeably smoother and quieter. So a 1" spacer didn't fix it, and I didn't really want a spacer in there anyway. And even with the spacer, aligning the pinion angle with the tranny angle didn't fix it.
SYE & DC driveshaft
I knew beforehand that I might need an SYE and a DC driveshaft, but I thought I could put it off for a while. I kept reminding myself that it's an LJ, maybe it won't need them. Wrong-O.
I installed an Advance Adapters Slip Yoke Eliminator (SYE) and a Tom Wood's Double Cardan (DC) driveshaft (stories for another day, perhaps). And removed the skid spacer, bolting the skid up against the frame. And lowered the exhaust hanger (see below). I tilted the rear pinion up to almost align with the driveshaft, about 1° low.
Verified that the shocks don't hit the lower spring perches, and the JKS track bar joint swivels safely in the axle-end bracket, and it doesn't hit the gas tank skid, and the fan doesn't hit the shroud. And my shifter is properly centered now (problem from installing MML, above). I can put the leather boot and bezel back in place, with plenty of clearance to shift into all gears.
Now, 70 MPH is nice and smooth, no more driveline vibes. And it has a partial tummy tuck — not flat, but considerably slimmer.