I would always suggest checking in with the JAX lab first. They have a nice database for plenty of their strains. This webpage introduces it and has links to the database: http://jaxmice.jax.org/jaxnotes/507/507a.html
Thanks for your answer. Unfortunately, Its so hard for me to find my answer from there. I want to know what is the average weights for each organ(i.e. Adrenal, intestine, pancreas,bladder, ...) of 40gr mouse.
I have downloaded a .csv file from the JAX lab for a very common background strain and can find lots of data for weights of heart, adrenal gland, brain. I would suggest it is worth mining their datasets if you have time, but realise it is not the quickest of tasks.