I just finished my rear disc conversion (downey) I now have 4-wheel disc brakes, . They work good,the front locks up before the rear. I installed everything 2#residual valve and a proportion valve.My booster is 30 yrs. old and I have a rebuilt master cylinder.I have acsess to a 88 4-runner booster and master,or 96 2wd tacoma booster&master for about the same price.which would be best ? & would they both bolt up to my 72 fj-40? Believe me I did use search!! thanks for any help.