This might get long...

I purchased this MOD tank for my 1987 Roland JC-77 to replace the Accutronics tank that is a direct replacement for the JC-120/JC-77 reverb tank. Long story short, the Accutronics replacement tank for the Roland JC-120/JC-77 does not sound anywhere near as good as the original reverb tank sounded before it failed. So the next option is to relocate the tank from the underside of the chassis to the bottom of the cabinet. To do that you need to de-solder the short send/receive cables from the board and make longer send/receive cables that reach the bottom of the cabinet. That sounds like more of a hassle than it actually is - and it is totally worth it. This tank sounds totally wonderful in a JC-77. It sounds even better than the original tank did before it stopped working.

NOTE: After relocating the tank and confirming that it works in it's new location I went back in and replaced the 10k linear reverb pot in my JC-77 with the 22k linear "Marshall style" pot Amplified Parts sells here. This is also an upgrade well worth doing if you feel your JC-77 does not give you enough reverb. I actually bought the 22k and the 50k linear pots because I wasn't sure which one would work best and give me what I wanted reverb wise. I just new the stock 10k pot does not give me enough reverb. With that said, I tried the 50k pot first. The reverb sounded glorious with the 50k up to 6 on the dial then would fizzle out beyond that. 50k proved to be too much so I took it out and put in the 22k. The 22k linear pot was perfect. Way better reverb than with the original 10k linear pot. However if you do increase that pot value, you will need to relocate the tank or you will get an unacceptable amount of hum in your reverb.