I've found this one..
SUMMER SQUASH PICKLES
8 c. sliced yellow squash
4 c. sliced onions
1 tbsp. salt
Put together in large bowl. Sprinkle salt over and let stand for 1 hour. DO NOT RINSE.
1 c. vinegar
1 3/4 c. sugar
1/2 tsp. celery seed
1/2 tsp. mustard seed
1/2 c. chopped peppers, optional
Bring to boil in a pan large enough to hold squash and onion mixture. After this is boiling add squash and onion and bring to a boil again. Let boil for 5 minutes, then put in jars and seal.