Shipbucket

As in the baseline, a single MCLWG replaced the forward 5-in gun. ASROC reloads were cut from 24 to 12-16 to add volume for the larger gun and its magazine.

A Spruance could accommodate a 29 round vertical launcher in place of her ASROC, and the 8-in gun (with 336 rounds) could replace here forward 5-in/54

In the simplest Knox-class LFS conversion, the 5-in/54 gun was replaced by a 155mm vertically loaded gun with 600 rounds, and a digital (hence more adaptable) Mk 86 or Mk 92 fire control system replaced the earlier analog Mk 68. Alternatively, in the second conversion option an 8-in/36 with 500 rounds could replace the 5-in gun; in the third option it could be replaced by a 9-in rocket launcher with 350 rounds. Nothing more could be done, because it as important that the Knox class retain the ASW capability represented by ASROC, which occupied the only other available launcher position.

There was some expectation, too, that the 155-mm gun could be adapted to other rolls, such as ASW (e.g., to fire sonobuoys and hydrostatically fused shells, which are in effect, depth bombs).

Among the proposals selected for further study was a naval version of Vought's Army MRLS 9-inch rocket launcher; the rockets would carry bomblets. MRLS, at the time called MARS (multiple army rocket system) had been rejected for the naval fire support role in 1970.

[A]nd the Vought 9-in rocket that could be fired from an ASROC launcher.

If I'm not mistaken the study came about when the last proper bombardment ship the USS Carronade was scrapped.

just rereading this..... a few questions are rising
- what could have been that 29 cell vertical launcher on the sprucan? an mk 41 VLS or another system?
- any details on that MLRS/MARS system? I couldn't even find the land based one... :$