nope, 88 is when they came over tothe early 90's style.

The bed rail was outside up until then.

 

Man, you guys have good eyes. I can't pick up anything from that....

 

Wrong. I have seen many external bedrails on '84 and newer 4x4's. External bedrails means the bed was made in Japan, and the internal bedrails mean the bed was made in the US and installed on the truck after it was imported.

 

Dude that truck looks like a perfect example of the early '84 hilux (truck). Looks very clean and well cared for too. they did have exposed bed rails all the way up to the change over to the 3 gen. (89-95) they had hooks on the '84s. that style of two-tone was factory spec. and the rims are correct for '84 and '85.
Places to check for rust are the seams of the box. that is lower rocker panel/box side & box side/top rail curve & tail gate. other wise they were a good solid truck. If it was regularly oil sprayed there should be no real rust issue though.
As previous posters have said check the drain lines from the sunroof for clogs (it is a peice of hose that runs from the sun roof down to the lower rocker panel [on some 4runners it ran down the a pillar and on some trucks it went down the b pillar i think]) in either case it connected to a body drain hole.
hope this helps Aviator