The gunbuggy was designed from scratch as a vehicle to carry what was at the time a brand new weapon, so a list of requirements would have been drawn up about 10 miles long to cover what was perceived by peace time engineers to be the basic requirements. Hence the prototype gunbuggy was released and thought to be ideal for the job.
Over a period of time set aside for "user evaluation" (standard process with all new products) a few shortfalls were discovered, such minor things as the muzzle blast obliterating the front of the vehicle and the recoil blast having the same effect on the rear section, hence mudguards and body tub were shortened. A lot of other minor problems were found (but remember that these problems were discovered in a "peaceful" home grown exercise environment) and these were duly rectified, and lo and behold eventually the gunbuggy as we know it emerged, on what was then the current GS vehicle, the S2.
Time marches on and the little gunbuggy performs above and beyond its expectations, an awesome new anti tank weapon suddenly has the added advantage of being highly mobile. The S2a is adopted by the Australian Army as the standard GS and it has quite a number of improvements and modifications over the almost civilian S2 as Dennis M mentioned, and as a result some of these differences show up on buggies that were produced on different platforms. The Army "gunbuggy mods" were standardized but the Land Rover bits underneath it changed with the model change, hence the 2" lift on a S2a, bonnet catches, brushguards etc etc.
So whilst still under a "peacetime exercise type" development, little compartments and holders were attached all over the place in various nooks and crannies to hold all the perceived pieces of equipment deemed necessary and all looked neat and tidy and seemed to be practical by all inspecting Officers and the likes of such.
Unfortunately when the little buggies eventually did go to war in South Vietnam, suddenly what seemed important in peacetime, like where to store a personal weapon, became irrelevant, in that most people I knew had this thing about keeping their weapons handy, rather than in the prescribed place.
This fact, plus the fact that the most prevalent spare parts held by any LAD or workshop stores would have been for the current S2a vehicles, so when a mudguard or bonnet or other body panel was damaged it was replaced by what was readily available, and that often would have been a standardized S2a part. Originally the guards for a gunbuggy were from a S2 and undrilled for recovery CES brackets. The lack of use of the 106 as a vehicular mounted weapon quite possibly made the requirement for the tools to be out of the muzzle blast area, nowhere near as important as it was originally thought.
Onslow still has one rifle clamp still fitted in the rear of the tub although it seems to be bent about 90 Deg or so. This is the only one still fitted to the vehicle as most others were removed before disposal.

As I inferred above, I have never seen it used as most people I knew held on to their personal weapons, and I am having trouble recalling whether the machine gunner even took his personal weapon with him as he had drawn the M60 and ammo from the Q store for the outing on a day by day basis.
Wire cutters were fitted by the local 1 Coy LAD and made out of stock standard star pickets. There is one reference to wire across the road in the Commanders Diaries, and written off as a kids prank, but it happened at least 6 times that I know of. (A lot of funny things happened that didn't actually get to the notice of the boss, but I am sure that any employee in any job is well aware of this. At our reunions we have sometimes show personal collections as slide shows every now and then and our OC is simply amazed, and the most common statement heard is; "But I never knew that happened!!")
Lights were painted with the yellow eyelids as a courtesy to the locals and applied at a unit level. South Vietnam was basically a French outpost, the second language was French, driving rules etc were French, and as a result headlights on a local car had a yellow lens, a bit like our fog lights. Our light were white (well Lucas white anyway) and threw the wrong way so the compromise reached was the yellow eyelids. This ceased in later days as left hand drive headlights were fitted to O/S bound vehicles.
Most buggies that were fitted with M60s were road going vehicles and contrary to popular belief it is no real great fun driving around with no wind screen fitted, especially in the bug infested tropics, winding in and out of convoys and local traffic.
Regards
Glen