Hi Rick

Definitely you need to specify the battery parameters (Voltage in V, capacity in Ah) and type of cells (PzS).
The best way is to get this information from the old batteries.
You should find them on the info plates, and the information should be like: 4PzS 550 48V or 4PzB 550 48V

It means, that the battery has 48V voltage, 550 Ah capacity and according to DIN standard (PzS) or British Standard (PzB) it has 4 positive plates in each cell.

Additionally you should define the external box dimesions (L x B x H), type of the socket (may be FEM or Anderson type, read the rated current from them; may be 80A, 160A, 320A) and eventually the length of the battery cable.

Basing upon this, every serious battery manufacturer should tailor the battery suitable for you.

Good luck