95 E320 Cab with 17k problems/questions

Hope I can get some advice. I have a 95 Cab with 17,300 mi- driven ocassionally in Florida. First, battery died several months ago after sitting for 6 weeks of nonuse (had last been replaced 12/2000 ). Battery was recharged then and I now have trickle charger when car not in use. Since then, however, car turns over very slowly when starting. Tested okay, but is it time for a new battery? Any advise on where to purchase and any specific brands other than oem ? Secondly, the past couple of times I have used the car, I notice a vibration/rattle when in in drive/reverse and car not moving. Seems more prominate on passenger side and can only hear inside car or through wheel well . Only present when car at standstill and in gear ( under load.). Had the oil changed this past week at independent Mercedes shop who tested battery and suggested my engine mounts may be going bad . Seemed odd at 17,300 mi. Thanks for any feedback.

[mbdoc]

Mileage is low for that type of failure, HOWEVER after 10 years of life that is the most likely cause of vibration!

TIME is a cars enemy just like mileage, most times people ignore suggested TIME intervals for maintenance & that causes problems just like HIGH mileage.

M.B. DOC,
Are there any signs of failure to look for? It is more of a rattle than the vibration I have experienced when having to replace motor mounts in the past ( almost like a rough idle ). I got underneath car as best as I could to see if maybe it was a loose heat shield etc but could not detect anything. The car has been stored in a climate controlled environment since new and shows no signs of wear or aging whatsoever ie. cracked rubber , fading etc. What should I expect to pay to replace them if this is indeed the problem? Also, any thoughts on the battery. It is oem now ( I am a big Mercedes oem parts believer ) but am thinking of leaning towards a battery with a longer warranty replacement period, maybe 3 years since the car sits so much. Any particular brands and how do they compare pricewise to oem ( quoted $125 for roadside assistance replacement ). Thanks again for any help.

[deanyel]

I just bought motor mounts for a 94 coupe, probably the same - $35 each (Sachs) for two - the rear mount even less - under $20 as I recall. It's not a difficult job - I would think less than 2 hours.