Whoa About $300 or more if you want genuine Toyota and can wait a few days which I strongly recommend if you plan to keep your Previa bec we have owned 5 Toyotas from brand new and the few times I tried saving money by using after market OEM parts that costs slightly less, well when it failures in the 13th month after warranty passed, it will make one think twice and be disappointed
Normally the below website shows the blow-up exploded diagram of the location and related & nearby parts but my guess is it has to do with the age (1995) of your vehicle....but yes I have had to have a distributor replaced before bec mechanic said plugs were not firing and if you follow spark plug wires in opposite direction, there you will find the distributor cap that sits on top of the distributor...
http://www.trademotion.com/partlocat...95&catalogid=1
You might want to check above LINK and consider when ordering & buying genuine Toyota parts that you need that the best deals on the internet for Toyota genuine parts are at 2 Toyota dealers in Texas: (i) Toyota of Dallas and (ii) Toyota of Richardson (TX) where prices are 30% of MSRP plus S&H. We have owned 5 Toyotas brand new and I have been dealing with them for years (unless it's an emergency or small dollar value) via facsimile and/or internet and they take credit card. They ship everywhere via Big Brown UPS and might possibly ship overseas.
At both of their websites, you just specify your Toyota vehicle the Year Model etc and then it is broken down into several categories and can also provide blowup expansion diagram so you know you order right part.
Hope the Above Info Helps & Best of Luck!