Ron provided this link:
http://texasindustrialelectric.com/relays.asp
and the following suggestions earlier in this thread.
15-133
SAS-4202
Continuous Duty Rating 200 Amp
SAS4202 / 15-108
15-132
SAS-4201
Continuous Duty Rating 100 Amp
Prestolite SAS4201
Be very careful doing this job. You will be working with a potentially dangerous amount of fault current if you do not get both sets of batteries isolated. Do not trust the disconnect switch until you have tested it, or better yet, just disconnect cables yourself carefully so you know the batteries are isolated before starting the job.
Russ