I recently did a swap to an LSD pumpkin and thought I do a write up on what was involved.
IDENTIFY AN LSD DIFFERENTIAL CARRIER (PUMPKIN)
The first thing is obviously to find an LSD pumpkin off another IS300 to swap. I was able to get one from the wreckers. There's already a lot of posts on how to identify an LSD pumpkin, but here's a summary:
M82 = 3.73:1 (MT) Open
M85 = 3.73:1 (MT) LSD
M96 = 3.91:1 (AT) Open
M98 = 3.91:1 (AT) LSD
If you're pulling it off a parts car, you can check the axle code on the drivers door sill:DOING THE SWAP
B01A = 3.73:1 (MT) Open
B01B or B01C = 3.73:1 (MT) LSD
B03A = 3.91:1 (AT) Open
B03B or B03C = 3.91:1 (AT) LSD
Ratchet with sockets - 10mm, 12mm, 14mm, 17mm
Wrenches - 14mm - need 2 of these!
HEX SOCKETS - 8MM, 12MM-3/8drive
ALLEN KEY - 12MM
+ Breaker bars, screw driver, hammer, usual
The manual recommends new 12MM Hex bolts and 17MM bolts for the diff
I recommend new 8MM Hex bolts for the axle shafts
Make sure your new diff is filled with fresh oil (1.2 L) and new drain and fill washers.
Lift the back of the car and secure it safely.
Remove the rear floor board cover. It's held on by 4 fasteners with 10mm heads.
Remove the rear sway bar.
i) Remove sway bar bracket - 12mm socket (If I remember correctly)
ii) Unbolt the sway bar from the endlink
ii) OR unbolt the bottom of the endlink from the control arm are remove the bar with the links still attached - 12mm socket
I chose to remove it with the endlinks attached because it will come out this way and you don't have to fiddle with holding the hex screw while under the car.
Remove the rear cross member from both sides. 14mm socket.
OPTIONAL. Remove the rear exhaust section (the muffler piece). You can get away without doing this but the exhaust does get in your way when you're trying to remove the axle bolts and when you're moving the diff in and out of position.
Remove the 6 hex bolts holding each axle to the diff. These are tight and hard to remove. You'll need a 8MM HEX socket on a breaker bar (allen key will not work). I used PB blaster a few days before the job and a heated them up right before trying to take them off. Hammer the hex socket into the bolt to ensure it's in there tight (...you do not want to strip these or you're screwed). Pull the e-brake to prevent the axle from rotating and loosen it. You'll probably only have access to one or two bolts at a time because the axle shaft gets in the way - you'll need to rotate the shaft and re-engage the ebrake to undo each one. Be patient, this part took me ~2 hours to remove all 12 bolts. You will want to replace these with new bolts when you put the new diff in.
You can pull the end of the axle shaft out now that the bolts are off. They'll need a bit of help from a hammer to loosen them from the collar. Zip tie the shaft so that it's out of way.
Remove the 4 bolts holding the prop shaft to the diff. These are 14MM. You'll need to use a wrench to hold the nut and and another wrench (or socket if you're lucky and can fit one) to undo the bolt.
Move the driveshaft and support it with a jackstand.
Remove the 3 Hex bolts hold the back of the diff. These are 12MM Hex bolts. Again, you'll need a Hex socket to loosen these. The tricky part here is that your socket and ratchet have to be short enough to get between the diff and the gas tank. You'll then have to switch to an even shorter tool (like an allen key) to finish removing them. (Don't try to use the ratchet and get it wedged like I did
Note: The manual indicates that these are non-reusable so I replaced them.
Put a jack under diff to support it and remove the last 2 bolts. 17MM heads I believe. You can carefully lower the diff and remove it from the car.
Note: these bolts are also indicated as non-reusable, but I didn't bother getting new ones.
Put your new diff in and assemble everything in the reverse order. Use the torque specs provided from the manual.