Any decent parts store will have a belt measuring "tool". Just get a belt that is an inch or two longer than the one you have.Mark...
hey mark ,
good job getting that PO b/s off ! 
instead of guessing here like the PO did or winging it with a arbitrary # of 2"
longer belt that might or might not fit again ?
i suggest another path :
- the Current OEM TOYOTA part # is
99343-11570-77 for a FJ60 P/S Drive Belt
- i used My 1990 Dealership Parts Dept. Fast Moving Paper parts Cataloger
specifically because i wanted to know and use the Oldest original correct TOYOTA Part # possible in case there is or was a part #'s suppression , that
could and does produce misleading needed parts research results often ...
- this fact is a topic for another stand alone thread...... 
- NOTE : I posted Below the Entire Land Cruiser Alternator & Fan , Power Steering , A/C and Air Pump Drive Belts Part# Application chart's information from 1/1961 - 8/1990 FJ40, FJ55 , FJ60, FJ62
This is Solid Tech Spec. Data all fellow Members can use as a future research
Tool for Needed Repairs involving every single Land Cruiser Drive Belt Original base line Part# ever made and used during these production Dates Range's ................
So, Print those pages out and save them in you Print Media Land Cruiser 3-Ring Binders / Folders etc ...........
- now back to mark
- This is a Good Current and available USA dealership / parts PDC stocking #
- see if your local Dealer can get you the correct TOYOTA OEM part for the Job ?
- if Not or it will back order a few days , like some Land Cruiser dedicated part#'s do often ..........
- then call your Local NAPA , or ADVANCE AUTO , Or other major AUTO parts Chain that Sells In-Stock The Drive Belt Brand
" BANDO " .
- BANDO , is the OEM Toyota Drive Belt parts maker for the 99343-11570-77 the dealership sells you ......fyi
- The Last 4 Primary Digits of a TOYOTA Land Cruiser FJ60 OEM TOYOTA Drive Belt are it's Length / Diameter Size spec's .........
- so : 99343-11570-77 = 1570mm , this translates into You very simply need
a 1570mm millimeter BANDO size spec. Cogged type Drive belt ......
- TOYOTA Drive Belt part# size spec's have a stated Tolerance in the Microfiche
of 5mm max -out , this means in English they can run up to or below the part# size spec's possibly 5mm or less either way long or short , i have NEVER
been screwed by a 5mm possible variation on any TOYOTA or BANDO Parts maker Drive belt in my life , so its a NON-Issue , except when u double verify the BANDO Belt Brand part # size spec. VS the last 4 primary #,s of the TOYOTA part# i will better explain below ......;
- also if u have a Southern States Farm Supply Store near you , they as a chain
are all Authorized BANDO Drive belt Distributors / Dealers nation wide , farm tractors , lawn mowers , etc , most use Cogged Drive belts same as a FJ60 , does 2F Engine
- I have had Much success sourcing various Vintage Toyota Cogged BANDO Drive Belts at My Local " Bowens Farm Supply store " , who are a SS / Southern States owned Chain type store .
- i simply went to BANDO.com , and in under 60 seconds identified the correct
BABDO part# , and also Double Verified the Size / Length Spec. of the Toyota
Primary Part# last 4 Digits Identification method i outlined for you above ....
- Your BANDO OEM parts Maker Brand Belt part # 5610
- your 5610 Belt is the same size spec. as the 99343-11570-77 ...........
- now u have 2 options on the table to obtain the same exact correct part for
the job , you know is made to fit your FJ60 Alternator and Power Steering application set up ...........
-, here are the resources and images i saved for your job scope at hand ......
good luck
