Revtek came up with this hardware package for it's 3" spacer kit.  The 2001-2002 Tacoma was lifting more than they would have liked so they devised this kit to lower the front diff.  Revtek indicates in their instructions to modify the stock skid plates and re-install them in manner that I do not think is very sound or strong.

Here are the actual Revtek install instructions:

DIFFERENTIAL DROP SPACER KIT 
(MANDATORY ON ALL 4-CYLINDER TACOMA'S FOR 2001-2002) 

1. Remove both skid plates under the front of the vehicle. Save the OEM bolts (total of nine (9) 12mm bolts). 

2. Remove factory 19mm x 7" long bolts and nuts, supporting the front differential. Save the OEM washers for step 3. 

3. Install Revtek spacers RTDDS-1 between the two front differential supports and front cross-member. Fasten to cross-member using new 1/2 x 8" long bolts and nuts (making sure to reuse the factory washers). 

4. Install the FRONT skid plate using three (3)OEM bolts on the front and two (2) new M8 x 35mm bolts in the rear. DO NOT TIGHTEN YET. 

5. To install the REAR skid plate, elongate the rear mounting holes with a file for fitment. Once holes are elongated, mount rear skid plate with OEM 12mm bolts. 

6. Torque all skid plate bolts to specs.

Stock Toyota front differential M14, 1.50 pitch bolts and washers.

Grade 8, 1/2" bolts with 1" solid steel spacers.

1" diff drop spacer installed on the 4Runner.  I have a now discontinued Rockstomper Type II front skid plate.  The shape of this skid plate allows the drop spacers to be installed and the skid plate is unaffected.  To properly drop the front diff in my opinion you need a front skid plate of this nature.  The stock Toyota 2 piece front skid plate will not work correctly.

New experimental spacer.  The spacer on the top is 15/16" across.  The lower spacer is tapered 7/8" to 1".  It seems to allow the stock washers and rubber to lay flatter.  Unfortunately the cutting on this spacer is quite difficult and is beyond the means of the equipment I have.