What you really need to ask is are they torque to yield bolts? not stretch!
ALL bolts stretch, the unknown part is where the bolt is on its stress/strain graph so you really need to rely on the manufactures workshop manual, if it states renew bolts then renew. If it doesn't then it's up to you! Personally I reused my cap bolts in my 4.6.
EVERYONE used to say to re-new the head bolts in the 1.8 rover k series - BUT in the manual Rover gave a maximum length spec for the head bolts - if the bolts are withing this spec they can be reused.
It's only a 'rule of thumb' regarding the torque to angle = torque to yield.
What is really important - and often not know is if the bolt is Torque To Yield? (TTY) bolts are designed to be stretched to a degree
that requires greater precision than can be achieved using torque measurement alone. The benefit is a more uniform amount of clamping
force being applied to the materials being joined..
Your spanner applies a 'torque' to the head of a bolt to tighten it. Tightening any fastener to an angle rather than a torque is generally more accurate/repeatable way to achieve a certain level of design stress in the fastener as it takes friction 'mostly' out of the equation.
From the Landrover 4.0-4.6 workshop manual:
. 6. Remove 2 bolts securing each bearing cap.
7. Remove bearing cap and bearing shell.
NOTE: Keep bearing caps and bolts in
their fitted order.
And doesn't mention about fitting new bolts when torquing up:
6. Fit bearing cap bolts and tighten to 20 Nm (15
lbf.ft) then a further 80 degrees.
I would be careful changing any bolts which clamp 'round things' with caps as if you are changing the clamping force you will be changing the roundness of these caps - really they should be torqued up with these new fasteners and honed/lined bored to ensure roundness.