I'm not a brake master by any means. But, (don't quote me on this) I think your V6 booster may be a dual diaphram, the other a single. Here you go, some yards that can deliver for not too much. Compliments of Car-Part.com

Quote
1990
Power Brake Booster
Toyota 4Runner BLUE,3VZ-E,4x4 A 502190 $25 Midwest Auto Parts USA-IA(Waterloo) E-mail 1-866-916-4600 / 1-319-287-4600
1991
Power Brake Booster
Toyota Truck 2.4, 6767 $22.5 East Bay Auto Parts USA-MI(Interlocken) E-mail 1-800-332-9156
1991
Power Brake Booster
Toyota Truck 3-91,22RE 005504 $20 All Japanese Recycling USA-UT(West-Jordan) E-mail 1-800-522-0444
1992
Power Brake Booster
Toyota 4Runner 2-92,3.0L 006165 $20 All Japanese Recycling USA-UT(West-Jordan) E-mail 1-800-522-0444
1990
Power Brake Booster
Toyota 4Runner 3-90,3.0L,SR5 005954 $20 All Japanese Recycling USA-UT(West-Jordan) E-mail 1-800-522-0444
1992
Power Brake Booster
Toyota 4Runner - STK#1602,73K,CLEAN TK 1602 $15 Maroney's Foreign Car and Parts USA-PA(Smithton) Request_Quote 1-800-245-7278 Request_Insurance_Quote


85 4Runner - With NEW Marlin 4.7 Gears!! It's a whole new beast!