I recently had to replace the battery in my 2004 XJ8 VDP. Saved some money by purchasing an Interstate MTP-93 and installed it myself. The only issue was that there is no hole for the vent tube in the stock battery location. The Interstate batteries have their vent hole in the middle front of the battery.

This photo shows the vent tube extention kit that came free with the battery. I purchased the battery at a Firestone dealer for about $147.




Here is the battery installed. Simple to replace:
1) disconnect Positive then negative terminals.
2) use socket set to remove bolts on the top brace
3) use socket to remove bolt for front hold-down below positive terminal
3) use socket to remove bolt for front hold-down below negative terminal
4) disconnect vent tube
5) pull out old battery, drop in new one
6) reverse process for replacing brace and front hold-downs

Note: The Interstate MTP-93 is not as tall as the stock battery so the carrying strap can go on top or below the brace bar. I chose the top.




Here's a close up showing that this battery does not have a hole to plug the vent tube back into the stock location. That's where the kit comes in. You can see the vent nipple in the center front of the battery. It is a strange oval shape so stretching the original tube over it will not work, plus it's just slightly too far away.



And here's the vent tube extention kit installed. It goes on very easy. I opted to tape the original plastic elbow to the top of the battery just so I'll have it for future use if needed. It seems to have a good grip on the vent nipple, but the brace bar pushes a little bit on it. I'll watch it and if it ever gets pushed off then I'll try remounting with it going under and behind the brace bar.



Have fun!

 

Interstate's website list the MTP-93 for VDPs and MTP-49/H8 for XJ8s. The 49/H8 is the correct battery for both vehicles, the vent hole is in the correct position.