My 94 R vented on the side. It came with a vent plug for one side, and I attached my existing vent tube and adapter to the other side (Passenger side if I recall correctly). I'd just stop by the local wally world and take a look at the batteries on the shelf to be sure. If you do buy, ask an employee to get a fresh one out of the back. Sometimes the visible batteries on the shelf can be pretty old and ratty.

 

If you're going to use a wet cell battery it must be vented as the OEM because the battery is inside the vehicle. Not an issue for Gel cells like the Optima. If you can't get the vented one from Walmart, Auto Zone sells the same size as OEM with the proper vent. Replaced mine with one of their batteries and it was same size and spec OEM and was vented. It is made by the same folks that make the Walmart version although I believe I paid something like $ 140 after the core exchange but got a 7 year warranty. Don't expect it to last that long but should get 4-5 years out of it.