https://www.braillebattery.com/index.php/braille/product_batteries/ml30c

Here ya go. Very similar in size. Amp hours read a bit low but it's equivalent to an 84 amp hour Lead Acid battery. That and nearly 2000 cranking amps.

Only $2100.

But yeah otherwise I'd go with the VARTA like Richard mentioned here and in that previous reply.