85 k5 gearbox question

[ozrulzk5]

Just replaced the gear box on my 85 k5 (4x4) and I noticed that the bolts going thru the frame have spacers on them. Seems to me like that would eat a hole the same size thru the frame before the bolt head hits the frame. My question is would it be wise to replace the bolts with shorter ones with washers to have a larger contact area or is this so the bolts will break if the gearbox gets into a bad strain without damaging the frame area????? any light on this area would great thanks